IMAT 2025 Answers & Worked Solution

Full explanation

The excerpt links three symptoms to three different organs: yellowing of the skin or eyes points to liver damage, while fever, rash and kidney enlargement point to kidney inflammation — and it explicitly warns that painful urination and lower back pain can signal this progressing toward kidney failure.

That last point is exactly what option B restates, so it’s the correct interpretation. The other four options each overreach or invent something the excerpt never says: option A turns a possibility ("may" occur) into a certainty, option C brings in the pancreas, which is never mentioned, option D flatly contradicts the leaflet’s own warning about painful urination, and option E claims a benefit for kidney-failure patients that the text never makes.

Full explanation

This passage credits Apulia’s ICT recovery to companies revising their internal processes and pushing further into digitalisation — Gianni Sebastiano’s own quote frames the pandemic as "the great lesson," the trigger that pushed firms to digitalize, not the direct cause of their growth. Revenue and profitability figures (Exprivia’s 5.4% growth, rising margins) back up that the sector is genuinely recovering, even while a shortage of trained professionals holds it back.

The question asks for the statement that is not correct. Options A, B, D and E all track the passage closely: process revision improved efficiency and profits (A), the sector grew despite the staffing shortage (B), the pandemic is credited as the lesson behind digitalization (D), and digitalizing processes fed back into growth (E). Option C overstates the case — the passage never says the pandemic itself "ensured" growth or that companies "transformed into digital companies"; it says the pandemic highlighted why digitalization matters, and that companies are now revising their processes as a result. That gap between what the passage says and what option C claims is what makes C the answer.

Full explanation

Leonardo is describing an animal that kills, then weeps loudly over the body, then eats it anyway — using that behaviour as a metaphor for hypocrisy: tears on the outside, cruelty underneath.

That description is a direct match for the crocodile: "crocodile tears" is a well-known idiom for exactly this kind of fake, self-serving sorrow, which is precisely why Leonardo reaches for this animal rather than any other predator. None of the other four options carries that association — lions, panthers, tigers and boas are all fierce hunters, but none of them come with a folk tradition of weeping over their kills. The correct answer is A, Crocodile.

Full explanation

The passage establishes three facts: kuru is caused by eating the brains of deceased relatives (Zigas’s 1955 discovery); Creutzfeldt-Jakob disease resembles kuru but isn’t confined to New Guinea and is sometimes mistaken for Alzheimer’s; and both kuru and CJD are caused by prions — infectious proteins that persist in tissue even after death.

Option E is the only statement that sticks to what’s actually written: the passage itself says CJD "is sometimes confused with diseases like Alzheimer’s," and since kuru and CJD share the same underlying cause and overlapping symptoms, mix-ups between all three are plausible. The other four options each add something the passage never claims: A turns "sometimes confused with" into "a stage of," B credits Zigas with a cure rather than a cause, C mislocates CJD as if it were tied to the same funeral practice as kuru, and D calls a prion a bacterium when the passage is explicit that it’s an infectious protein.

Full explanation

Given statement: "The number two is a prime number."

The statement asserts the existence of at least one prime number: 2. Nothing in the statement says anything about other numbers. (We know there are other prime numbers but in solving questions like this, we only consider what is written in the question. )

Exclusion of other options Option B: Contradicted by the given statement. So, incorrect.

Option C: Not deducible: the statement says nothing about numbers other than 2.

Option D: Contradicted by 2 being prime.

Option E: Not deducible; statement only mentions 2.

Excluding the other options, the correct option is A.

Full explanation

This is a classic modus tollens: "If P, then Q" combined with "not Q" lets you validly conclude "not P" — nothing more, nothing less. Here P is "today is Saturday" and Q is "I am a philosopher." Since statement 2 rules out Q ("I am not a philosopher"), the only thing we can validly conclude is not-P: today is not Saturday — option B.

Option A claims the opposite of what the logic gives us. Option C picks one specific day (Friday) when the true conclusion only rules Saturday out — any of the other six days remains possible, so naming Friday specifically goes further than the premises allow. Option D just restates statement 2 itself rather than deducing anything new, and option E is wrong simply because a valid conclusion (B) does exist.

Full explanation

Four people share a square table, one on each side, so everyone has a left neighbour, a right neighbour, and one person seated directly across. We’re told Alberto sits to the left of Beatrice, and that Alberto is not seated to the right of Carlo.

Working through those two constraints pins every seat down, as the diagram above shows, and only option A survives: Daniela is seated to the right of Carlo.

Option B fails because Carlo actually sits across from Alberto, not Beatrice. Option C fails because Daniela sits to the left of Alberto, not to the left of Beatrice. Option D fails because Alberto sits to Beatrice’s left, not her right. Option E fails because Beatrice sits across from Daniela, not Alberto.

Full explanation

Three pills — blue, red, green — go into three same-coloured boxes, with two rules: no pill sits in the box matching its own colour, and the blue pill specifically avoids the green box too.

Since the blue pill can’t go in the blue box (rule one) and can’t go in the green box (the extra rule), it has only one place left: the red box.

That fills the red box, so now the green pill can’t go in the green box (rule one) and can’t go in the red box (already taken by blue) — leaving only the blue box for it.

Which leaves the red pill for the one box still open: the green box.

So: blue pill → red box, green pill → blue box, red pill → green box — exactly option E.

Full explanation

Clock shows 3:00 PM (hour hand at 3, minute hand at 12).

One full rotation of the minute hand = 60 minutes = 1 hour. So, 1.75 rotations = 1 hour 45 minutes.

3:00 PM + 1 h 45 min = 4:45 PM

Full explanation

During lactic acid fermentation, pyruvic acid is reduced directly by NADH to form lactate as an end product, regenerating NAD+ with no release of CO2. Thus, the correct option is option A.

The other options describe changes that don’t happen at this step: pyruvate isn’t oxidized here (oxidation happens later, in the separate, oxygen-dependent conversion of pyruvate to acetyl-CoA, which fermentation bypasses entirely), and no decarboxylation occurs either, since avoiding CO2 release is exactly what lets fermentation regenerate NAD+ quickly without a functioning electron transport chain. Phosphorylation and dephosphorylation aren’t involved at all, since no phosphate group is added to or removed from pyruvate in this reaction — only electrons and a proton are transferred, from NADH to pyruvate, which is precisely what "reduction" means.

Pearson Chapter 10 cellular respiration

Full explanation

Glycolysis is a 10-step pathway that occurs in the cytoplasm. Overall, for 1 glucose molecule, 2 ATP molecules, 2 NADH molecules, and 2 pyruvates are formed.

Analysis of the given options

Option A: Incorrect. Phosphofructokinase catalyses the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate (Kinase in the enzyme name refers to adding a phosphate group to a substrate). No step directly converts fructose-1,6-diphosphate to dihydroxyacetone phosphate (DHAP).

Option B: Incorrect. Triose phosphate isomerase catalyses the conversion of DHAP to glyceraldehyde-3-phosphate, which are isomers of each other.

Option C: Correct. During the steps of the glycolysis of one glucose molecule, 2 NAD+ are reduced into NADH, transferring high-energy electrons for later ATP production in cellular respiration.

Option D: Incorrect. The glycolysis pathway does not contain a carbon reduction step. Glucose, a 6-carbon molecule, is converted into 2 pyruvates (3-carbon molecules) without any CO2 release.

Option E: Incorrect. No FADH2 production occurs in the glycolysis pathway.

Full explanation

For each acetyl-CoA molecule that enters the Kreb cycle, the cycle produces 2 molecules of CO2, 3 molecules of NADH, 1 molecule of FADH2, and 1 molecule of ATP (or GTP), along with regenerating the starting molecule oxaloacetate. Therefore, the correct option is option A.

The other four options each swap one of these numbers for a wrong one: option B swaps the NADH and FADH2 counts (it should be 3 NADH and 1 FADH2, not the other way around); option C keeps the right coenzyme counts but inflates CO2 to 3 (the cycle releases exactly 2 CO2 per acetyl-CoA — the 2 carbons that entered as acetyl-CoA are what eventually leave as those 2 CO2 molecules); option D repeats that same CO2 error and also doubles the GTP to 2 (only one substrate-level phosphorylation step happens per turn of the cycle); and option E lowers NADH to 2 and raises FADH2 to 2, which doesn’t match either coenzyme’s actual yield.

Full explanation

Generally, there are 2 types of phosphorylation: substrate-level phosphorylation and oxidative phosphorylation. Substrate-level phosphorylation involves the direct transfer of a phosphate group from a phosphorylated intermediate (a substrate) to ADP, forming ATP. Oxidative phosphorylation occurs in the inner mitochondrial membrane, and generally it is a process that uses reduced coenzymes to make ATP. Oxidative phosphorylation involves oxidation of NADH and FADH2 and movement of electrons through coenzymes and storing electrochemical gradient energy, which is then used by ATP synthase to produce ATP through chemiosmosis.

Analysis of the given options Option A: Incorrect. The process mentioned is β-oxidation, where fatty acids are oxidized into 2-carbon molecules (acetyl-CoA), not oxidative phosphorylation. Option B: Incorrect. The process mentioned is the deamination and the urea cycle. Oxidative phosphorylation does not directly involve biomolecules like carbohydrates or proteins. Option C: Correct. This option correctly describes oxidative phosphorylation. Option D: Incorrect. Oxidative phosphorylation is the final stage of catabolism, not anabolism. Option E: Incorrect. Fatty acid synthesis occurs in the cytosol, not in the mitochondria, and it is an anabolic process.

Full explanation

Cytochromes are electron carrier proteins between ubiquinone and oxygen in the electron transport chain. Their prosthetic group, called a heme group, has an iron atom that accepts and donates electrons. The electron transport chain has several types of cytochromes, each named "cyt" with a letter and number to distinguish it as a different protein with a slightly different electron-carrying heme group.

Analysis of the given options Option A: Correct. Cytochromes are part of the respiratory chain. Option B: Incorrect. They only move electrons, not whole hydrogen atoms (that's NAD and FAD which carry whole hydrogen atoms) Option C: Incorrect. ATP synthase makes ATP, not cytochromes Option D: Incorrect. They are essential participants of oxidative phosphorylation, not inhibitors. Option E: Incorrect. Glycolysis happens in the cytosol and does not use cytochromes.

Full explanation

Collagen is the most abundant structural protein in the body. It forms extracellular fibers in connective tissue (bone, cartilage, skin, tendons). It is secreted by cells (like fibroblasts) and functions outside the cell, not inside or in membranes.

Analysis of the given options Option A: Incorrect — collagen functions outside the cell, not inside. Option B: Incorrect — collagen is not part of the membrane. Option C: Correct — collagen is a major component of the extracellular matrix. Option D: Incorrect — Think filaments are composed of myosin, not collagen.  Option E: Incorrect — collagen is not found in the nucleus.

Full explanation

Skeletal muscle contraction is switched on by a rise in intracellular calcium. When a nerve impulse arrives, Ca²⁺ is released from the sarcoplasmic reticulum and binds to troponin, a small regulatory protein sitting on the thin (actin) filament. That binding changes troponin’s shape, which pulls the neighbouring tropomyosin strand out of the way and exposes the myosin-binding sites on actin — the trigger that lets the cross-bridge cycle, and contraction, begin.

So calcium binds troponin directly, which makes B the correct answer. Myosin (A) and actin (D) are the two filaments that slide past each other during contraction, but neither one is what calcium itself binds to. Tropomyosin (C) only moves as a knock-on effect of troponin’s shape change, one step downstream of the calcium-binding event being asked about. Vimentin (E) is an unrelated intermediate filament protein found in the cytoskeleton generally, with no role in this calcium-signalling step.

Full explanation

Muscle contraction relies on the sliding filament model: actin (the thin filament) and myosin (the thick filament) slide past each other, powered by the myosin head, which also carries the ATPase activity responsible for hydrolyzing ATP.

The cross-bridge cycle proceeds as follows:

1. ATP binds to myosin, causing myosin to release actin (the actin-myosin complex dissociates).
2. ATP is hydrolyzed to ADP and phosphate, and the myosin head swings back into a high-energy, "primed" position, ready for the next power stroke.
3. Calcium binds to troponin, which shifts tropomyosin out of the way and exposes the actin-binding sites, allowing myosin to bind actin again.
4. The power stroke occurs: the myosin head pulls the actin filament inward, generating the sliding motion of contraction.
5. A new ATP molecule binds to the myosin head, the cross-bridge detaches, and the cycle repeats.

Analysis of the given options

Option A: Correct — ATP binding causes myosin to release actin.

Option B: Incorrect — ATP binding triggers dissociation of the complex, not its formation.

Option C: Incorrect — calcium binding to troponin allows actin-myosin binding, not dissociation.

Option D: Incorrect — the ATPase activity belongs to myosin, not actin.

Option E: Incorrect — tropomyosin blocks the actin-binding sites; it does not hydrolyze ATP.

Full explanation

The Bohr effect describes how increased CO₂ and H⁺ (lower pH) in tissues reduces hemoglobin's affinity for oxygen. This enhances oxygen release where it's most needed (active tissues).

Key point: oxygen delivery increases, but oxygenated hemoglobin decreases in the blood.

Analysis of the given options Option A: Incorrect — Bohr effect is about hemoglobin function, not RBC count. Option B: Incorrect — affinity decreases, so fewer hemoglobin molecules are oxygenated. Option C: Correct — low pH and high CO2 promote oxygen release, lowering oxygenated hemoglobin. Option D: Incorrect — it is a shift in oxygen binding, not denaturation. Option E: Incorrect — Irrelevant.

Full explanation

The definition given — something that speeds up a reaction and comes out unchanged at the end — is the textbook definition of a catalyst, so the correct answer is D. Enzymes are simply the biological catalysts your body runs on.

The other four terms describe something related but not the same thing: a modulator or effector adjusts how much an enzyme does its job (typically by binding away from the active site), rather than being the rate-accelerating substance itself; a cofactor is a non-protein helper (a metal ion or small organic molecule) that an enzyme often needs before it can work at all, not the catalytic substance in its own right; and cholesterol is a structural lipid with no catalytic role whatsoever.

Full explanation

Competitive inhibition happens when an inhibitor molecule resembles the substrate closely enough to compete directly with it for the enzyme’s active site — whichever one binds first occupies the site and blocks the other. Because it’s a direct competition for a limited resource, adding enough extra substrate can out-compete the inhibitor and still reach the enzyme’s normal maximum rate (Vmax stays the same), though more substrate is now needed to get there, which is why the apparent Km rises.

That makes option A the correct definition. Option B has the binding backwards — a competitive inhibitor binds the enzyme’s active site itself, not the substrate. Option C describes non-competitive or allosteric inhibition instead, where the inhibitor binds a separate site rather than competing with the substrate at all. Option D describes blocking product release from the active site, a different mechanism that isn’t what defines competitive inhibition. Option E invents an "enzyme-cholesterol complex," which plays no role in enzyme kinetics.

Full explanation

Analysis of the given options Lipase: Breaks down fats (triglycerides), not proteins. Amylase: Breaks down starch/carbohydrates into sugars. Peptidase: Correct. It hydrolyzes peptide bonds in proteins. Isomerase: Catalyzes structural rearrangements of molecules, not digestion. Transaminase: Catalyzes amino group transfer in amino acid metabolism, not digestion.

Full explanation

Oxidative phosphorylation depends on two different kinds of participants working together across the inner mitochondrial membrane: large integral membrane protein complexes (Complexes I–IV of the electron transport chain, plus ATP synthase) that stay fixed in place, and smaller mobile carriers — coenzyme Q (ubiquinone) within the membrane and cytochrome c on its outer face — that physically shuttle electrons from one fixed complex to the next.

That combination of fixed complexes and mobile carriers is why option E is correct, and it’s exactly what each "exclusively" option leaves out. Option C misses the mobile carriers entirely. Option D describes peripheral (loosely attached, non-membrane-embedded) proteins, which isn’t the mechanism at work here. Option B is wrong because the electron-transport-chain complexes sit embedded in the inner membrane itself, not floating free in the mitochondrial matrix — the matrix is where the Krebs cycle’s soluble enzymes work instead. Option A is wrong for an even more basic reason: nuclear proteins play no part in oxidative phosphorylation, which is carried out entirely by mitochondrial-membrane machinery.

Full explanation

During biological oxidation (glycolysis, Krebs cycle, β-oxidation), electrons are transferred to coenzymes: NAD⁺ → NADH and FAD → FADH₂. These reduced coenzymes must be reoxidized to keep metabolism running. This happens in the electron transport chain (respiratory chain), where electrons are passed through complexes and ultimately reduce oxygen to water. In anaerobic conditions, the fermentation process reoxidizes the reduced enzymes.

Analysis of the given options Option A: Incorrect. Fatty acid beta-oxidation generates reduced coenzymes; it does not reoxidize them. Option B: Correct. NADH and FADH2 are oxidized in the ETC, releasing energy for ATP synthesis. Option C: Incorrect. Electrons do not go directly to oxygen; they pass through ETC complexes first. Option D: Incorrect. Reduced enzymes are not reoxidized in ATP synthase. Also, ATP synthase uses the proton gradient, not direct electron transfer. Option E: Incorrect. Hormone synthesis is unrelated to reoxidizing coenzymes.

Full explanation

The high-energy reserve compound that is present in muscles is creatine phosphate (phosphocreatine), which can provide immediate energy before glycolysis or oxidative phosphorylation kicks in.

A common point of confusion is creatinine phosphate, but this is actually a waste product of creatine and does not serve as an energy reserve.

Carnitine phosphate: Carnitine is involved in fatty acid transport into mitochondria, not high-energy phosphate storage.

Glucose-1-phosphate: Intermediate in glycogen breakdown, not a direct high-energy phosphate donor.

Phosphofructokinase: That's an enzyme in glycolysis, not an energy-storage compound.

Full explanation

The liver is the central metabolic hub: detoxification, amino acid metabolism, gluconeogenesis, and the urea cycle. Processes like glycolysis, beta-oxidation, and the Krebs cycle happen in many tissues, but the urea cycle occurs exclusively in the liver, spanning both the mitochondria and the cytoplasm of hepatocytes, because the liver is the only organ that contains all the necessary enzymes for the complete urea cycle. In the case of transamination, significant activity can be seen not only in the liver, but also in the kidneys, heart, and skeletal muscle cells.

Therefore, the correct option is option A.

Full explanation

Humans mainly store long-term energy as triglycerides (fats) as a more compact reservoir of fuel because they are highly reduced molecules with minimal water.

Analysis of the given options Option A: Incorrect. Triglycerides have more calories and less water. Option B: Incorrect. More calories. Option C: Correct. This is why fat is the most efficient energy store. Option D: Incorrect. Less water. Option E: Fats contain less oxygen than proteins or carbohydrates.

Full explanation

A lysosome is a membranous sac of hydrolytic enzymes that many eukaryotic cells use to digest (hydrolyze) macromolecules. These enzymes work best in an acidic environment (pH < 7). Lysosomes are formed by budding from the golgi apparatus. Function: Phagocytosis (Digest materials taken into the cell) and Autophagy (Recycle intracellular material) Malfunction is linked to many diseases (e.g, Tay-Sachs)

Analysis of the given options Option A: Incorrect. Lysosomal storage diseases are well documented. Option B: Incorrect. Enzymes work best at acidic pH, not alkaline. Option C: Incorrect. Lysosomes form from the Golgi, not the smooth ER. Option D: Correct. This correctly describes how lysosomes originate. Option E: This is the role of ribosomes on the rough ER, not lysosomes.

Full explanation

In eukaryotes, DNA is mainly in the nucleus, but also in mitochondria (animals + plants) and chloroplasts (plants + algae). Mitochondria and chloroplasts are semi-autonomous and have their own circular DNA + ribosomes. Other organelles (ER, Golgi, lysosomes, etc.) do not contain DNA. Prokaryotes do not have a nucleus — their DNA is in the cytoplasm, in the nucleoid.

Analysis of the given options Option A: Correct. All three organelles do contain DNA. Option B: Incorrect. Mitochondria and chloroplasts also contain DNA, not just RNA. Option C: Incorrect. Most organelles do not have DNA. Option D: Incorrect. Protein synthesis does happen in the rough endoplasmic reticulum, but DNA is not located in the RER. Option E: Incorrect. Prokaryotes lack a nucleus. Their DNA is in the nucleoid region.

Full explanation

The plasma membrane is a phospholipid bilayer with proteins. Its main role is selective permeability: it controls what enters and leaves the cell, maintaining homeostasis.

Analysis of the given options

Option A: Incorrect. The plasma membrane does not synthesize proteins. It is ribosomes.

Option B: Incorrect. It is the mitochondria that produce energy via the electron transport chain.

Option C: Correct. This is the plasma membrane's core function: transport of ions, nutrients, signalling molecules, and waste.

Option D: Incorrect. That's the nucleus in eukaryotes or the nucleoid region in prokaryotes.

Option E: Incorrect. Movements involves cytoskeleton, cilia, flagella, not the plasma membrane itself.

Full explanation

Exergonic reactions are reactions with a negative Gibbs free energy. They release energy and can occur spontaneously.

Analysis of the given options Option A: Incorrect. The mentioned process is the photosynthetic light reactions. Option B: Incorrect. The mentioned processes are endothermic reactions. Option C: Correct. This is the exact definition of exergonic reactions. Option D: Incorrect. In exergonic reaction, energy must come from transforming reactants. Option E: Incorrect. Some exergonic reactions involve the synthesis of new compounds (like ATP hydrolysis driving biosynthesis), but not always.

Full explanation

Bone tissue is kept in balance by two opposing cell types: osteoblasts, which build new bone by secreting collagen and depositing minerals into the matrix, and osteoclasts, which do the opposite job, breaking bone tissue back down. Remembering the pair together makes the terms easy to keep straight — osteoBLASTs BUILD, osteoCLASTs CLEAR away.

That makes option A correct. Options B and D both describe resorption — breaking bone down and releasing its minerals — which is the osteoclasts’ job, not the osteoblasts’. Option C reaches for a real phenomenon (bone can act as a mineral buffer for blood pH) but misattributes it as an osteoblast function rather than a broader property of bone tissue. Option E confuses osteoblasts with the blood vessels that actually run through bone and deliver nutrients.

Full explanation

Insulin is a peptide hormone secreted by the beta-cells of the pancreas (Islets of Langerhans). Its main role is to promote storage of nutrients — glucose, fatty acids, and amino acids — after a meal.

Analysis of the given options Option A: Correct. Insulin triggers translocation of GLUT4 glucose transporters — moving them from internal storage vesicles to the muscle cell membrane — which is what stimulates glucose uptake. Option B: Incorrect. Insulin promotes synthesis; glucagon/epinephrine stimulates glycogen breakdown. Option C: Incorrect. It's a peptide hormone composed of two polypeptide chains linked by 2 disulfide bonds. Steroid hormones are like cortisol, aldosterone, sex hormones. Option D: Incorrect. Insulin stimulates fatty acid synthesis (lipogenesis) Option E: Incorrect. Insulin comes from the pancreas, not the adrenal.

Full explanation

Two closely related equations tend to get mixed up here. The ideal gas equation is PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature — this is the equation being asked about, and it describes a single state of a gas. The combined gas law, (P₁V₁)/T₁ = (P₂V₂)/T₂, is a different tool: it compares the same fixed amount of gas across two different states (before and after a change in pressure, volume or temperature), rather than defining the equation of state itself.

Only option A, PV = nRT, is the actual equation of state — the other four options rearrange the same four letters into combinations that don’t correspond to any real gas law.

Full explanation

Recall the rules H = +1, O = -2 Sum of oxidation numbers = 0 for neutral molecule Analysis of each compound Option A: Cl₂ : Diatomic element → oxidation number = 0 Option B: HClO₂ (chlorous acid) Let Cl = x +1+x+(−4) = 0 ⟹ x = +3 (Correct)

Option C: HCl +1+x = 0 ⟹ x=-1 Option D: HClO (hypochlorous acid) +1+x+(−2) = 0 ⟹ x = +1 Option E: HClO₃ (chloric acid) +1+x+(−6) = 0 ⟹ x = +5

Full explanation

Analysis of the given options Option A: Oxidation numbers can be negative. Examples: Cl⁻ in NaCl (-1), O²⁻ in H₂O (-2). Option B: Oxidation numbers can be positive. Examples: Na⁺ in NaCl (+1), Fe³⁺ in Fe₂O₃ (+3). Option C:  the average oxidation number can be fractional so, can be a number with a decimal point. In Pb3O4, the average oxidation number of lead is +8/3 which is +2.67. Option D: Correct. Oxidation numbers are never irrational. Option E: Oxidation number can be 0 for elements in their standard state. Example: O₂, H₂, N₂ all have oxidation number 0.

Full explanation

Analysis of the given options Option A: Correct. NaCl = Na⁺ + Cl⁻ ions arranged in a crystal lattice. Held together by strong electrostatic forces (ionic bonds). Option B: Incorrect. Molecular solids = discrete molecules held by van der Waals forces, dipole-dipole, or H-bonds. Example: ice (H₂O), dry ice (CO₂). NaCl is not made of molecules. Option C: Incorrect. Metallic solids = metal atoms in sea of delocalized electrons. Example: Fe, Cu, Al. NaCl is ionic, not metallic. Option D: Incorrect. Covalent network solids = atoms covalently bonded in a continuous network. Example: diamond, SiO₂. NaCl has ionic bonds, not covalent network. Option E: Incorrect. Amorphous solids = no long-range order (non-crystalline). Example: glass, gels. NaCl forms a regular crystalline lattice, so it's not amorphous.

Full explanation

Two opposing size trends operate in the periodic table.

Across a period (left to right): atomic number increases, so more protons pull the electrons — which are still in the same shell — in more tightly. Atomic radius decreases.

Down a group (top to bottom): each row adds a new electron shell farther from the nucleus, so atomic radius increases.

Put together, radius increases moving right to left (the reverse of the period trend) and top to bottom (the group trend as stated) — exactly option E.

Options A and C have the horizontal direction backwards: radius decreases left to right, not increases. Option B reverses the vertical trend too. Option D's claim that the horizontal trend is "irregular" doesn't match reality — it's a smooth, steady decrease across each period.

Full explanation

A pure covalent bond is a bond that forms between two atoms of the same element. Same element → same electronegativity → ΔEN = 0 → pure covalent Examples: H₂, O₂, N₂.

Exclusion of the other options Option A: Two atoms with quite similar electronegativity could still have some electronegativity difference. So, this could not be said to be a pure covalent bond. Option C: This forms ionic or polar covalent bonds, not pure covalent. Option D: Electronegativity is a property of atoms. There is no atom without the electronegativity property. Option E: Ions form ionic bonds, not covalent bonds.

Full explanation

Monoprotic weak acid, K_a = 1.0 × 10⁻⁵, concentration C = 0.001 M.

HA ⇌ H⁺ + A⁻

Let x be the amount of HA dissociated:

K_a expression:

K_a = [H⁺][A⁻] / [HA] = (x × x) / (0.001 − x) = x² / (0.001 − x)

Assuming 0.001 − x ≈ 0.001:

K_a = x² / 0.001

x = √[(1 × 10⁻⁵)(1 × 10⁻³)] = √(1 × 10⁻⁸) = 1 × 10⁻⁴ M

So, pH = −log[H⁺] = −log[1 × 10⁻⁴] = 4

Correct answer: D) 4

Full explanation

KBr = salt of strong acid (HBr) + strong base (KOH). Such salts dissociate completely: KBr → K⁺(aq) + Br⁻(aq) Neither K⁺ nor Br⁻ hydrolyzes in water. So the solution is neutral. Neutral solution at 25 °C → pH = 7. Concentration (0.7 M) doesn't matter here, because ions don't affect water's neutrality.

Full explanation

Heat + 2FeCl₃ (s) ⇌ 2FeCl₂ (s) + Cl₂ (g)

Key points: Heat on the left → reaction is endothermic forward. Solids (FeCl₃, FeCl₂) do not affect equilibrium position by changing their amount (their activities are constant). Only gases and aqueous species appear in the equilibrium constant. Thus, Cl₂(g) and temperature changes are relevant.

Analysis of the given options Option A: Incorrect. Adding/removing a solid does not shift equilibrium. Option B: Incorrect. Again, solids don't matter in Le Chatelier's principle for equilibrium shifts. Option C: Incorrect. Cooling removes heat → system shifts to the left (exothermic direction) to produce more heat. To shift right, we'd need to heat (since forward is endothermic). Option D: Correct. Increasing a product (Cl₂ gas) → equilibrium shifts left to consume Cl₂. Option E: Incorrect. Same issue: solids don't change equilibrium position.

Full explanation

Analysis of the given options Option A: Correct. Activation energy (Ea) = minimum energy required to reach the transition state. It's the "hurdle" reactants must overcome before products can form. Option B: Incorrect. That's the ΔH (enthalpy change), not activation energy. Option C: Incorrect. No such definition exists in chemical kinetics. a is about the energy barrier, not a KE--PE comparison. Option D: Incorrect. Energy released = related to ΔH, not Ea. Option E: Incorrect. activation energy is absorbed (input), not released.

Full explanation

The benzene molecule (C₆H₆) has a planar, hexagonal ring structure of six carbon atoms. Every carbon in benzene bonds to two neighbouring carbons and one hydrogen (three σ bonds). That requires three sp² orbitals (formed from 1 s + 2 p) arranged trigonal-planar (≈120°). Therefore, the correct answer is E.

Full explanation

Analysis of the given options Option A: Correct. Glycogen is made only of glucose monomers → a homopolysaccharide. Option B: Incorrect. Heteropolysaccharides contain different monomers (e.g., hyaluronic acid with N-acetylglucosamine + glucuronic acid). Glycogen = glucose only → not hetero. Option C: Incorrect. Disaccharides = 2 monomers (e.g., maltose, sucrose, lactose). Glycogen = many glucose → polysaccharide. Option D: Incorrect. In animals: storage polysaccharide = glycogen. In plants: storage polysaccharide = starch. So glycogen is not shared by both. Option E: Incorrect. Polypeptide = chain of amino acids. Glycogen = carbohydrate, not protein.

Full explanation

There are two important oxidation states for iron: Ferrous — Iron II (Fe2+) and Ferric — Iron III (Fe3+)

CO₃²⁻ is the carbonate ion with a -2 charge.

In FeCO₃, to balance, Fe must be +2, not +3 → so not ferric.

The correct name is iron(II) carbonate, aka ferrous carbonate.

Exclusion of other options Iron pentacarbonyl:  Fe(CO)₅, a coordination compound with CO ligands, not carbonate. Iron oxide: Oxide means a compound with O²⁻ only (e.g., FeO, Fe₂O₃).

Full explanation

An orbital can hold a maximum of two electrons. According to Pauli's exclusion principle, no two electrons in an atom can have the same set of four quantum numbers, meaning a maximum of two electrons can occupy an orbital, and they must have opposite spins. One must have a spin of +1/2 and the other -1/2.

Therefore, the correct answer is B. Two with antiparallel spins

Full explanation

The basic structure of an amino acid is composed of a central carbon surrounded by one amine group (-NH2), one carboxyl group (-COOH), one hydrogen group, and one side chain R group. Side chain R defines the type of amino acid.

Analysis of the given options Option A: Correct. The key point to notice here is that the amine group and the amino group can be used interchangeably in amino acids because the amino group refers to the primary amine group.

Option B: Incorrect. The solubility of amino acids mainly depends on the side chain R attached to the central carbon. If the side chain is largely hydrophobic, e.g., in Isoleucine, the amino acids would be insoluble in water. If the side chain is hydrophilic, e.g., serine, the amino acids would be soluble in water.

Option C: Incorrect. Hexane, being a nonpolar solvent, nonpolar amino acids like isoleucine would be soluble in that solvent, not all amino acids.

Option D: Incorrect. Carbohydrates are made of monosaccharides (sugars), not amino acids. Amino acids are building blocks of proteins.

Option E: Incorrect. Acidity and basicity largely depend on the side chain R of amino acids. It is incorrect to say that they have no acid/base activity. As an example, Aspartate and glutamate, having a carboxyl group as a side chain, show acidic properties.

Full explanation

Step 1 — find the domain: √(2x) is only defined when the expression inside is non-negative, so 2x ≥ 0, giving x ≥ 0.

Step 2 — since both sides of √(2x) < 1 + x are non-negative for x ≥ 0, we can square both sides without flipping the inequality: (√(2x))² < (1 + x)², so 2x < 1 + 2x + x².

Subtracting 2x from both sides: 0 < 1 + x², i.e. x² + 1 > 0.

Step 3 — interpret: x² + 1 is always positive for every real x (since x² ≥ 0), so this simplified inequality is true for every real number. But we must still respect the domain restriction x ≥ 0 found in Step 1.

So the solution is ∀x ≥ 0.

Hence, the correct answer is (B).

Full explanation

Test each option by substituting u = sin x or v = cos x and checking whether the resulting quadratic inequality holds for the whole valid range [−1, 1].

Option A: with u = sin x, u² + u − 2 ≤ 0. The quadratic u² + u − 2 = 0 has roots u = 1 and u = −2 (opens upward, so ≤ 0 between its roots): −2 ≤ u ≤ 1. Since sin x always lies in [−1, 1], which is entirely inside [−2, 1], this inequality is always satisfied.

Option B: with v = cos x, v² − v − 2 ≥ 0 holds for v ≤ −1 or v ≥ 2. Taking cos x = 0 gives 0 − 0 − 2 = −2 < 0, which fails ≥ 0 — not always true.

Option C: tan²x − 2tan x + 1 = (tan x − 1)² > 0 fails exactly when tan x = 1 (e.g. x = 45°) — not always true.

Option D: with u = sin x, 2u² − u − 1 > 0 holds for u < −½ or u > 1. Taking sin x = 0 gives 0 − 0 − 1 = −1 < 0, which fails — not always true.

Option E: with v = cos x, 2v² + v − 1 < 0 holds for −1 < v < ½. Taking cos x = 1 gives 2 + 1 − 1 = 2, which is not < 0 — not always true.

Only option A is satisfied for every real x.

Hence, the correct answer is (A).

Full explanation

The Cartesian product of two sets A and B, denoted A × B, is the set of all ordered pairs (a, b) where a ∈ A and b ∈ B.

For example, if A = {1, 2} and B = {3, 4}, then A × B = {(1,3), (1,4), (2,3), (2,4)}.

Hence, the correct answer is (C).

Full explanation

This trinomial fits the perfect-square pattern (x − y)² = x² − 2xy + y².

Here a² is the square of a, 4b² is the square of 2b, and the middle term −4ab equals −2 × a × 2b.

So a² − 4ab + 4b² = (a − 2b)².

Hence, the correct answer is (A).

Full explanation

Let the height BC = h, so the base AB = (5/4)h.

Perimeter P = 2(AB + BC): 72 = 2((5/4)h + h) = 2((9/4)h) = (9/2)h.

So h = 72 × 2/9 = 144/9 = 16 cm.

Then AB = (5/4) × 16 = 20 cm.

So AB = 20 cm, BC = 16 cm.

Hence, the correct answer is (B).

Full explanation

A linear equation is "determined" if it has a unique solution. Solving for x: 3x + a = 3, so 3x = 3 − a, giving x = (3 − a)/3.

The coefficient of x is 3, which is never zero, so we can always isolate x and find a unique solution regardless of the value of a.

Hence, the correct answer is (C).

Full explanation

A linear equation is impossible when the coefficient of x is zero but the constant term is non-zero, giving a false statement (a contradiction) with no solution.

Here, if a + 3 = 0, i.e. a = −3, the equation becomes (0)x = 5, i.e. 0 = 5, which is false — there is no solution. For any other value of a, the equation can be solved for x normally.

Hence, the correct answer is (B).

Full explanation

Convert speeds to m/s: v₁ = 120 km/h = 100/3 ≈ 33.33 m/s; v₂ = 80 km/h = 200/9 ≈ 22.22 m/s.

The relative speed at which A closes the gap on B is v₁ − v₂ = 100/3 − 200/9 = (300 − 200)/9 = 100/9 m/s.

In 60 seconds, the distance closed is (100/9) × 60 = 6000/9 ≈ 666.67 m.

Since 666.67 m > the initial 500 m gap, car A has not only caught up to car B but overtaken it within that one minute.

Hence, the correct answer is (D).

Full explanation

Resistors in series add directly, so each branch's resistance is R_series = 10R.

The 100 identical branches (each 10R) are in parallel, so 1/R_eq = 100 × (1/10R) = 10/R, giving R_eq = R/10.

Hence, the correct answer is (D).

Full explanation

Conventional current is defined as the direction of flow of positive charge, so for current flowing left to right, the conventional current direction is left to right.

In a metal wire, current is actually carried by electrons (negative charges). Since electrons are negative, their movement in one direction is equivalent to positive charge moving in the opposite direction. So for the conventional current to be left to right, the electrons must physically move right to left.

Protons are fixed in the metal lattice and do not move; only electrons are mobile.

Hence, the correct answer is (E).

Full explanation

Gravitational acceleration at distance r from a planet's centre is g' = GM/r².

If R is the Earth's radius, a distance of 3R from the surface means a distance of R + 3R = 4R from the centre.

So g' = GM/(4R)² = GM/(16R²) = (1/16)(GM/R²) = (1/16)g, since g = GM/R² at the surface.

Hence, the correct answer is (E).

Full explanation

Segment 1 (constant speed): acceleration is zero, so net force is zero. The engine force forward must exactly balance friction: F1 = F_friction = 2000 N.

Segment 2 (accelerating at a = 2.0 m/s²): the net force is ΣF = ma = 2000 kg × 2.0 m/s² = 4000 N. This net force is the engine force minus friction: F2 − 2000 N = 4000 N, so F2 = 4000 + 2000 = 6000 N.

Hence, the correct answer is (A).

Full explanation

A fluid at rest cannot sustain shear stresses, so it can only exert forces perpendicular (normal) to any surface it contacts. This perpendicular force per unit area is what's called pressure.

The force is not "in any direction" (option B rejected) and not "parallel" (option C rejected, since that would require a shear force, which a static fluid cannot exert). It isn't "no forces, only pressure" (option D rejected, since pressure is precisely the mechanism by which the force is exerted) and the forces are certainly not zero (option E rejected).

Hence, the correct answer is (A).