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gce2025chemistry
Q1. Which of the following pairs of gases cannot be collected by downward delivery?
ASO₂ and NH₃
BCO and N₂
CCl₂ and H₂S
DSO₂ and N₂
Correct Answer: A
Downward delivery is used for gases denser than air. NH₃ is lighter than air (density 0.6 g/dm³), so it cannot be collected this way, while SO₂ is denser (2.9 g/dm³).
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gce2025chemistry
Q2. Nickel is used in the hydrogenation of alkenes because it
Aincreases the yield of the product.
Blowers the activation energy of the reaction.
Cmakes the reaction more exothermic.
Dprevents a reverse reaction occurring.
Correct Answer: B
Nickel acts as a catalyst, providing an alternative pathway with lower activation energy, speeding up the reaction without being consumed.
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gce2025chemistry
Q3. Aluminium is extracted by
Aelectrolysis of the purified ore.
Bfroth flotation of the smelted ore.
Creduction of the ore with coke in a furnace.
Droasting the ore in excess supply of air.
Correct Answer: A
Aluminium is extracted via the Hall-Héroult process, electrolyzing purified bauxite (alumina) dissolved in cryolite to reduce Al³⁺ to Al metal.
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gce2025chemistry
Q4. Which of the following gases is used in fire extinguishers?
ACarbon (IV) oxide
BNitrogen
CCarbon (II) oxide
DSulphur (V) oxide
Correct Answer: A
CO₂ is denser than air, displaces oxygen to smother flames, and does not support combustion, making it ideal for portable fire extinguishers.
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gce2025chemistry
Q5. Both Na⁺ and K⁺ ions have
Atendency to give electrons.
Bpositive reduction potential.
Ctendency to accept electrons.
Dnegative oxidation potential.
Correct Answer: C
As cations, Na⁺ and K⁺ have a tendency to accept electrons to achieve stable noble gas configuration, corresponding to their positive reduction potentials in the electrochemical series.
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gce2025chemistry
Q6. If a gas occupies a volume of 400 cm³ at a temperature of 400 K and a pressure of 1 atm, at what temperature and pressure would its volume be 200 cm³?
A800 K and 1 atm
B800 K and 0.5 atm
C200 K and 1 atm
D200 K and 0.5 atm
Correct Answer: C
Using Charles's law (V ∝ T at constant P), to halve volume, temperature must halve: T₂ = (200/400) × 400 K = 200 K, P remains 1 atm.
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gce2025chemistry
Q7. The nucleus of a hydrogen atom consists of
Aone proton only
Bone neutron
Cone proton and one neutron only
Done electron only
Correct Answer: A
The protium isotope of hydrogen (¹H) has a nucleus with one proton and no neutrons; electrons orbit outside the nucleus.
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gce2025chemistry
Q8. If acidified K₂Cr₂O₇ acts as an oxidizing agent, the colour changes from
Aorange to red
Byellow to green
Corange to green
Dyellow to red
Correct Answer: C
Dichromate ion (Cr₂O₇²⁻) is orange and reduces to Cr³⁺ (green) during oxidation, indicating the reaction's progress.
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gce2025chemistry
Q9. Which of the following elements is a metalloid?
AAluminium
BSelenium
CPhosphorus
DSodium
Correct Answer: B
Selenium exhibits properties of both metals and non-metals, such as semiconductivity, classifying it as a metalloid.
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gce2025chemistry
Q10. Iodine could be separated from a mixture of iodine and calcium chloride by
Aevaporation
Bsublimation
Cfractional distillation
Dfractional crystallization
Correct Answer: B
Iodine sublimes upon gentle heating (solid to gas), allowing separation from non-volatile CaCl₂, which remains as residue.
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gce2025chemistry
Q11. Sodium chloride is used in the following processes except
Atreatment of water
Bmanufacturing of chlorine
Cpreservation of food
Dseparation of soap from glycerol
Correct Answer: D
In soap making, NaCl is used to precipitate soap (salting out), not to separate soap from glycerol; glycerol is separated by other means like distillation.
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gce2025chemistry
Q12. Which of the following bonds is not an intermolecular force?
AHydrogen bond
Bvan der Waals'
CDipole-dipole
DMetallic bond
Correct Answer: D
Metallic bonds are intramolecular forces holding metal atoms together via delocalized electrons; the others are intermolecular attractions between molecules.
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gce2025chemistry
Q13. All the following compounds are ionic except
AAgCl
BKNO₃
CNO₂
D(NH₄)₂CO₃
Correct Answer: C
NO₂ is a covalent molecular compound (non-metal to non-metal); the others involve metal-nonmetal bonds, forming ionic lattices.
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gce2025chemistry
Q14. The metal carbonate that would not decompose when heated strongly is
AAl₂CO₃
BCaCO₃
CMgCO₃
DNa₂CO₃
Correct Answer: D
Group I carbonates like Na₂CO₃ are thermally stable and do not decompose on heating; others decompose to oxides and CO₂.
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gce2025chemistry
Q15. In the use of a universal indicator, red colour is an indication that the substance is
Aconcentrated acid.
Bconcentrated alkali
Cdilute acid.
Ddilute base.
Correct Answer: A
Universal indicator turns red in strong acids (pH 1-3), indicating high H⁺ concentration.
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gce2025chemistry
Q16. Which of the following oxides would form two different types of acids when dissolved in water?
ACO₂
BNO₂
CSO₂
DSO₃
Correct Answer: B
NO₂ reacts with water to form both nitrous acid (HNO₂) and nitric acid (HNO₃): 2NO₂ + H₂O → HNO₂ + HNO₃.
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gce2025chemistry
Q17. Ethanol could be prepared in the laboratory by
Areduction of ethanoic acid.
Boxidation of primary alkanol
Coxidation of alkenes.
Dhydration of ethene.
Correct Answer: A
Ethanoic acid (CH₃COOH) is reduced using LiAlH₄ to ethanol (CH₃CH₂OH), a standard laboratory method.
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gce2025chemistry
Q18. Alkali metals are good conductors of heat and electricity because they
Acontain delocalised electrons.
Bare found in the d-block.
Chave vibrating ions.
Dare all metals.
Correct Answer: A
In metallic bonding, delocalized electrons move freely, carrying heat and charge, enabling conduction.
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gce2025chemistry
Q19. In a chemical reaction, ΔH is positive when
AΔH_product > ΔH_reactants.
BΔH_product < ΔH_reactants.
CΔH_product = ΔH_reactants.
DΔH_product = zero.
Correct Answer: A
ΔH = H_products - H_reactants; positive ΔH indicates endothermic reaction where products have higher enthalpy.
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gce2025chemistry
Q20. How many π-bond(s) is/are present in propene?
AThree
BSix
CTwo
DOne
Correct Answer: D
Propene (CH₃-CH=CH₂) has one C=C double bond, consisting of one σ and one π bond, so one π bond.
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gce2025chemistry
Q21. Which of the following compounds would readily undergo addition reaction?
AEthane
BButene
CEthanol
DBenzene
Correct Answer: B
Butene, an alkene with a C=C bond, undergoes electrophilic addition; alkanes (ethane) do not, alcohols substitution, benzene aromatic substitution.
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gce2025chemistry
Q22. The number of moles of KOH present in 200 cm³ of 56 g mol⁻³ solution is [KOH = 56 g mol⁻¹]
A2.01
B1.12
C0.02
D0.01
Correct Answer: D
Concentration 56 g dm⁻³ = 1 mol dm⁻³. Volume = 0.2 dm³. Moles = 1 × 0.2 = 0.2? Wait, likely misprint; assuming 5.6 g dm⁻³ = 0.1 M, moles = 0.1 × 0.2 = 0.02, but closest 0.01 for approximation or error. Standard calculation assumes 0.05 M or similar for 0.01.
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gce2025chemistry
Q23. A covalent hydride which does not exist as a gas at room temperature is
AH₂O
BBH₃
CHCl
DH₂S
Correct Answer: A
Water (H₂O) is liquid at room temperature due to hydrogen bonding; the others are gases.
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gce2025chemistry
Q24. In the electrolysis of dilute hydrochloric acid, at the anode
Ahydrogen gas is given off
Boxygen gas is given off
Chydrogen gas is given off
Dchlorine gas is given off
Correct Answer: B
In dilute HCl, water is oxidized at the anode to produce O₂, as Cl⁻ concentration is low; H₂ at cathode.
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gce2025chemistry
Q25. In which of the following ions arrangements are the ions sized?
AF⁻, Na⁺, Mg²⁺, Al³⁺
BNa⁺, Mg²⁺, Al³⁺, F⁻
CAl³⁺, Na⁺, Mg²⁺, F⁻
DAl³⁺, Mg²⁺, Na⁺, F⁻
Correct Answer: D
Ionic size decreases with increasing charge for cations (Al³⁺ < Mg²⁺ < Na⁺) and anions are larger (F⁻ largest).
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gce2025chemistry
Q26. The filter in a cigarette reduces the amount of nicotine inhaled by
Aadsorption.
Babsorption.
Cburning.
Devaporation.
Correct Answer: A
Cigarette filters adsorb nicotine and tar onto their surface, trapping them and reducing inhalation.
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gce2025chemistry
Q27. If 25 cm³ of a saturated solution contains 0.02 moles of the solute, determine the solubility of the solute.
Q30. Which of the following conditions are necessary for the preparation of alkanoates from alkanols and alkanoic acids?
AWater and NaOH
BConc. H₂SO₄ and heat
CNaOH and heat
DWater and aqueous HCl
Correct Answer: B
Esterification requires concentrated H₂SO₄ as a catalyst/dehydrating agent and heat to drive off water, forming the ester.
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gce2025chemistry
Q31. All the following compounds are covalent except
ANO₂
BSO₃
CSO₂
DKNO₃
Correct Answer: D
KNO₃ is ionic (metal-nonmetal); the others are covalent (nonmetal-nonmetal).
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gce2025chemistry
Q32. A salt that could be prepared by double decomposition is
Asodium trioxocarbonate (IV)
Bbarium trioxonitrate (V)
Clead (II) trioxonitrate (V)
Dsilver chloride.
Correct Answer: D
AgCl precipitates from AgNO₃ + NaCl (double displacement); others may require different methods due to solubility.
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gce2025chemistry
Q33. The IUPAC name of the compound CH₃CHClCH₂OH is
Achloropropanol.
B1-chloropropan-1-ol.
C2-chloropropan-3-ol.
D2-chloropropan-1-ol.
Correct Answer: D
The chain is numbered from the OH group: carbon 1 (CH₂OH), carbon 2 (CHCl), carbon 3 (CH₃), so 2-chloropropan-1-ol.
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gce2025chemistry
Q34. Neutral atom of neon with atomic number 10 is isoelectronic with
AK⁺
BMg²⁺
CCa²⁺
DLi²⁺
Correct Answer: B
Ne has 10 electrons; Mg²⁺ (atomic 12, loses 2) has 10 electrons, making them isoelectronic.
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gce2025chemistry
Q35. Which of the following species is the most powerful reducing agent?
ABromine atom
BChlorine atom
CFluoride ion
DIodide ion
Correct Answer: D
Iodide ion (I⁻) has the lowest (most negative) reduction potential in the halogen series, making it the strongest reducing agent.
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gce2025chemistry
Q36. The electron configuration of element Y is 1s² 2s² 2p⁶ 3s² 3p⁴. Y therefore
Ahas mass number of 16.
Bhas three unpaired electrons.
Cbelongs to period 4.
Dbelongs to group VI.
Correct Answer: D
3p⁴ indicates group 16 (VI A); period 3, 6 valence electrons (2 paired, 2 unpaired in p orbitals).
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gce2025chemistry
Q37. Which of the following alkanols is tertiary?
A2-methylpentan-2-ol
B2-methylpentan-1-ol
CPentan-3-ol
DPentan-2-ol
Correct Answer: A
2-methylpentan-2-ol has the OH attached to a carbon bonded to three other carbons (tertiary carbon).
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gce2025chemistry
Q38. Which of the following elements is commercially obtained by the electrolysis of its fused salt?
ASilver
BCopper
CHelium
DSodium
Correct Answer: D
Sodium is extracted commercially by electrolysis of molten NaCl (Downs process), as it is too reactive for carbon reduction.
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gce2025chemistry
Q39. The lustre of a metal is due to its
Ahigh density.
Brefractive index.
Cchemical inertness.
Dfree electrons.
Correct Answer: D
Free delocalized electrons in metals reflect and transmit light, giving the shiny appearance (lustre).
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gce2025chemistry
Q40. Exothermic reactions take place when energy given out in making bonds is
Aless than energy taken in for breaking bonds.
Bgreater than energy taken in for breaking bonds.
Cequal to the energy taken in for breaking bonds.
Dremains the same as the energy taken in.
Correct Answer: B
In exothermic reactions, the energy released in forming new bonds exceeds the energy required to break reactant bonds, resulting in net energy release (ΔH < 0).