Filter by exam, subject and year then load questions instantly
Advertisement
post-utme2019chemistry
Q1. The molecular shape and bond angle of water are respectively
Alinear, 180°
Bbent, 109.5°
Ctetrahedral, 109.5°
Dbent, 105°
Correct Answer: D
Water (H₂O) has 2 bonding pairs and 2 lone pairs on the central oxygen atom. Lone pair–lone pair repulsion compresses the bond angle from the ideal tetrahedral 109.5° to approximately 105°, giving water a bent/V-shape. Answer: D.
Generating AI explanation...
AI Explanation
post-utme2019chemistry
Q2. When chlorine water is exposed to bright sunlight, the following products are formed
AHCl(aq) and Cl₂
BHOCl(aq) and Cl₂
CHCl(aq) and O₂
DHOCl(aq) and O₂
Correct Answer: C
Chlorine water contains Cl₂, HCl, and HOCl in equilibrium: Cl₂ + H₂O ⇌ HCl + HOCl. On exposure to bright sunlight, the HOCl decomposes: 2HOCl → 2HCl + O₂. The overall result is the production of HCl(aq) and O₂. This is why chlorine water bleaches more rapidly in sunlight.
Generating AI explanation...
AI Explanation
post-utme2019chemistry
Q3. Which of the following describes the chemical property of acids?
ANone of the above
BAcid + XCO₃ → Salt + H₂O + NH₃
CAcid + NaOH → Normal salt + CO₂
DAcid + XₙCO₃ → Salt + H₂O + CO₂
Correct Answer: D
A standard chemical property of acids is their reaction with carbonates. Acid + metal carbonate → salt + water + carbon dioxide. Example: 2HCl + Na₂CO₃ → 2NaCl + H₂O + CO₂. Option B wrongly gives NH₃ as a product; Option C wrongly gives CO₂ from acid + NaOH. Answer: D.
Generating AI explanation...
AI Explanation
post-utme2019chemistry
Q4. A certain hydrocarbon on complete combustion at s.t.p produced 89.6 dm³ of CO₂ and 54 g of water. The hydrocarbon should be?
AC₆H₆
BC₄H₁₀
CC₅H₁₀
DC₄H₆
Correct Answer: D
Moles of CO₂ = 89.6/22.4 = 4 mol → 4 carbon atoms. Moles of H₂O = 54/18 = 3 mol → 6 hydrogen atoms (3 × 2). Molecular formula = C₄H₆. This matches option D (C₄H₆), which is butyne or butadiene.
Generating AI explanation...
AI Explanation
post-utme2019chemistry
Q5. By what amount must the temperature of 200 cm³ of nitrogen at 27°C be increased to double the pressure if the final volume is 150 cm³? (Assume ideality)
A150°C
B177°C
C75°C
D120°C
Correct Answer: A
Using the general gas law: P₁V₁/T₁ = P₂V₂/T₂. T₁ = 27 + 273 = 300 K, V₁ = 200 cm³, P₂ = 2P₁, V₂ = 150 cm³. T₂ = T₁ × (P₂ × V₂)/(P₁ × V₁) = 300 × (2 × 150)/200 = 300 × 1.5 = 450 K. Increase in temperature = 450 - 300 = 150 K = 150°C.
Generating AI explanation...
AI Explanation
post-utme2019chemistry
Q6. Which of the following gases contains the least number of atoms at s.t.p?
A1 mole of butane
B4 moles of chlorine
C3 moles of ozone
D7 moles of argon
Correct Answer: D
Total atoms = moles × atoms per molecule. Butane (C₄H₁₀): 1 × 14 = 14 mol atoms. Chlorine (Cl₂): 4 × 2 = 8 mol atoms. Ozone (O₃): 3 × 3 = 9 mol atoms. Argon (Ar): 7 × 1 = 7 mol atoms. Argon has the fewest total atoms at 7 mol atoms.
Generating AI explanation...
AI Explanation
post-utme2019chemistry
Q7. In the reaction between sodium hydroxide and tetraoxosulphate (VI) solutions, what volume of 0.5 molar sodium hydroxide would exactly neutralize 10cm³ of 1.25 molar tetraoxosulphate (vi) acid?
Q8. If acidified potassium dichromate (VI) (K₂Cr₂O₇) acts as oxidizing agent, the colour changes from
Ayellow to green
Borange to green
Cyellow to red
Dorange to red
Correct Answer: B
Acidified potassium dichromate (VI) is orange in colour due to Cr₂O₇²⁻. When it acts as an oxidizing agent, Cr is reduced from +6 to +3, forming Cr³⁺ ions which give a green colour. Therefore the colour changes from orange (Cr₂O₇²⁻, Cr⁶⁺) to green (Cr³⁺) when it oxidizes a substance.
Generating AI explanation...
AI Explanation
post-utme2019chemistry
Q9. 2CO + O₂ → 2CO₂. Calculate the volume of the resulting mixture at the end of the reaction, if 50 cm³ of carbon (II) oxide was exploded in 100 cm³ of oxygen.
A75 cm³
B125 cm³
C100 cm³
D50 cm³
Correct Answer: B
From the equation 2CO + O₂ → 2CO₂, ratio CO:O₂:CO₂ = 2:1:2. 50 cm³ CO reacts with 50/2 = 25 cm³ O₂ to produce 50 cm³ CO₂. Excess O₂ remaining = 100 - 25 = 75 cm³. Total volume of mixture = CO₂ + excess O₂ = 50 + 75 = 125 cm³.
Generating AI explanation...
AI Explanation
post-utme2019chemistry
Q10. The IUPAC name for CH₃CH₂COOCH₂CH₃ is
Amethylpropanoate
Bethylethanoate
Cethylpropanoate
Dmethylethanoate
Correct Answer: C
CH₃CH₂COOCH₂CH₃ is an ester. The acid part is CH₃CH₂COO- (propanoic acid, 3 carbons), and the alcohol part is -CH₂CH₃ (ethyl group, 2 carbons). IUPAC name: ethyl propanoate. The alcohol portion names the ester first (ethyl), followed by the acid portion (-anoate): ethylpropanoate.
Generating AI explanation...
AI Explanation
post-utme2019chemistry
Q11. The IUPAC nomenclature of the compound H₃C - CH(CH₃) - CH(CH₃) - CH₂ - CH₃
A3,4-dimethylhexane
B2,3-dimethyl pentane
C2-ethyl hexane
D2,3-dimethylhexane
Correct Answer: D
The longest carbon chain: CH₃-CH(CH₃)-CH(CH₃)-CH₂-CH₃ contains 6 carbons (hexane). Methyl groups are on C2 and C3. IUPAC name: 2,3-dimethylhexane. Numbering from the end closest to the substituents gives positions 2 and 3, not 3 and 4.
Generating AI explanation...
AI Explanation
post-utme2019chemistry
Q12. Which of the following properties increases from left to right along the period but decreases down the group in the Periodic Table? i. Atomic Number ii. Ionization energy iii. Metallic character iv. Electron affinity
Aii and iii only
Bii and iv only
Ciii and iv only
Di and ii only
Correct Answer: B
Across a period (left to right): ionization energy increases, electron affinity increases, metallic character decreases, atomic number increases. Down a group: ionization energy decreases, electron affinity decreases. Properties that increase left to right AND decrease down the group are ionization energy (ii) and electron affinity (iv). Answer: B.
Generating AI explanation...
AI Explanation
post-utme2019chemistry
Q13. Which of the following will give a precipitate with an aqueous solution of copper (I) chloride?
ABut-2-ene
BBut-1-ene
CBut-2-yne
DBut-1-yne
Correct Answer: D
Copper (I) chloride (CuCl) in ammoniacal solution reacts with terminal alkynes (those with a C≡C-H at the end of the chain) to give a red/brown precipitate of a copper acetylide. But-1-yne (HC≡C-CH₂-CH₃) has a terminal triple bond and reacts to give a precipitate. But-2-yne has an internal triple bond and does not react.
Generating AI explanation...
AI Explanation
post-utme2019chemistry
Q14. Which of the following is a set of neutral oxides?
AN₂O, H₂O, CO
BN₂O, SO₂, CO
CN₂O, Na₂O, ZnO
DN₂O, SO₃, NO
Correct Answer: A
Neutral oxides do not react with acids or bases to form salts. N₂O (nitrous oxide), H₂O (water), and CO (carbon monoxide) are all neutral oxides. SO₂ is acidic; Na₂O is basic; ZnO is amphoteric; SO₃ is acidic; NO can behave as a neutral oxide in some contexts but it is debated. Option A (N₂O, H₂O, CO) is the most consistent set of neutral oxides.
Generating AI explanation...
AI Explanation
post-utme2019chemistry
Q15. Which of the following is a physical change?
AExposing white phosphorus to air
BBurning kerosene
CDissolving calcium in water
DFreezing ice cream
Correct Answer: D
A physical change alters the form or appearance of a substance without changing its chemical composition. Freezing ice cream involves a change of state (liquid to solid) — no new substance is formed. Exposing white phosphorus to air, burning kerosene, and dissolving calcium in water all involve chemical reactions that produce new substances.
Generating AI explanation...
AI Explanation
post-utme2019chemistry
Q16. Which of the following alkaline earth metals react more spontaneously with water?
ACalcium
BBeryllium
CMagnesium
DStrontium
Correct Answer: D
Reactivity of alkaline earth metals with water increases down Group II: Be < Mg < Ca < Sr < Ba. Strontium (Sr) is the most reactive among the options given, reacting vigorously and spontaneously with cold water to give Sr(OH)₂ and H₂. Be barely reacts with water; Mg reacts only with steam; Ca reacts with cold water but less vigorously than Sr.
Generating AI explanation...
AI Explanation
post-utme2019chemistry
Q17. Which of the following represents the kind of bonding present in ammonium chloride?
Aionic only
Bcovalent only
Cionic and covalent
Ddative covalent
Correct Answer: C
NH₄Cl contains both ionic and covalent bonding. Within the NH₄⁺ ion, there are three ordinary N-H covalent bonds and one dative covalent bond (from NH₃ + H⁺). Between NH₄⁺ and Cl⁻, the bonding is ionic (electrostatic attraction between oppositely charged ions). So NH₄Cl has both ionic and covalent bonding.