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1
Chemistry Medium

Which type of chemical bond involves atoms sharing electrons unequally due to difference in electronegativity?

  • ANon-polar covalent bond
  • BPolar covalent bond
  • CMetallic bond
  • DIonic bond
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Correct Answer: Option B — Polar covalent bond
Explanation: A polar covalent bond forms when electrons are shared unequally between atoms of different electronegativities creating partial positive and negative charges on the molecule as in water.
Submitted by: PaperMCQs
2
Chemistry Medium

Which type of formula shows all the bonds between atoms in a molecule?

  • AEmpirical formula
  • BStructural formula
  • CMolecular formula
  • DIonic formula
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Correct Answer: Option B — Structural formula
Explanation: A structural formula shows all the atoms in a molecule and the bonds between them either as a displayed formula showing each bond or as a condensed structural formula.
Submitted by: PaperMCQs
3
Chemistry Medium

Which indicator is colourless in acidic solution and pink in alkaline solution?

  • ALitmus
  • BMethyl orange
  • CUniversal indicator
  • DPhenolphthalein
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Correct Answer: Option D — Phenolphthalein
Explanation: Phenolphthalein is colourless in acidic and neutral solutions but turns pink to magenta in alkaline solutions and is commonly used as an indicator in acid-base titrations.
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4
Chemistry Hard

Which law states that the amount of substance deposited during electrolysis is directly proportional to the quantity of electricity passed?

  • ABoyle's Law
  • BGay-Lussac's Law
  • CAvogadro's Law
  • DFaraday's First Law of Electrolysis
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Correct Answer: Option D — Faraday's First Law of Electrolysis
Explanation: Faraday's First Law of Electrolysis states that the mass of a substance deposited at an electrode during electrolysis is directly proportional to the quantity of charge passed.
Submitted by: PaperMCQs
5
Chemistry Hard

What is the chemical formula for chloroform a once common anaesthetic?

  • ACH2Cl2
  • BCCl4
  • CCHCl2
  • DCHCl3
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Correct Answer: Option D — CHCl3
Explanation: Chloroform has the chemical formula CHCl3 and was historically used as an anaesthetic and is now used as a solvent in chemical synthesis and laboratory work.
Submitted by: PaperMCQs
6
Chemistry Medium

Which type of reaction in organic chemistry involves replacing a hydrogen atom with another atom or group?

  • AElimination
  • BSubstitution
  • CAddition
  • DHydrolysis
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Correct Answer: Option B — Substitution
Explanation: Substitution reactions replace one atom or group in a molecule with another as seen when chlorine substitutes hydrogen in methane under UV light producing chloromethane.
Submitted by: PaperMCQs
7
Chemistry Medium

What is the formula for calculating moles from mass and molar mass?

  • AMoles equals mass times molar mass
  • BMoles equals molar mass divided by mass
  • CMoles equals mass divided by molar mass
  • DMoles equals mass times volume
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Correct Answer: Option C — Moles equals mass divided by molar mass
Explanation: Moles are calculated by dividing the mass of a substance in grams by its molar mass in grams per mole providing the fundamental calculation in all stoichiometry problems.
Submitted by: PaperMCQs
8
Chemistry Medium

Which process is used to separate crude oil into useful fractions based on different boiling points?

  • AFractional distillation
  • BChromatography
  • CCrystallisation
  • DFiltration
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Correct Answer: Option A — Fractional distillation
Explanation: Fractional distillation separates crude oil into fractions with different boiling points in a fractionating column producing petrol kerosene diesel lubricating oil and bitumen.
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9
Chemistry Medium

Which element is liquid at room temperature and is the only non-metal element in this state?

  • AMercury
  • BBromine
  • CGallium
  • DCaesium
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Correct Answer: Option B — Bromine
Explanation: Bromine is the only non-metal element that exists as a liquid at room temperature appearing as a reddish-brown volatile liquid with a pungent irritating smell.
Submitted by: PaperMCQs
10
Chemistry Hard

What is the term for the energy required to remove one electron from a gaseous atom?

  • AElectron affinity
  • BElectronegativity
  • CLattice energy
  • DIonisation energy
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Correct Answer: Option D — Ionisation energy
Explanation: Ionisation energy is the minimum energy required to remove one electron from a gaseous atom in its ground state with first ionisation energy increasing across a period and decreasing down a group.
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