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71
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.
Submitted by: PaperMCQs
72
Chemistry Hard

Which element in Group 1 of the periodic table reacts most vigorously with water?

  • ALithium
  • BSodium
  • CCaesium
  • DPotassium
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Correct Answer: Option C — Caesium
Explanation: Caesium the heaviest stable Group 1 alkali metal reacts most vigorously with water due to its large atomic radius and low ionisation energy resulting in an explosive reaction.
Submitted by: PaperMCQs
73
Chemistry Medium

Which type of organic reaction involves the addition of bromine water across a carbon to carbon double bond?

  • AAddition
  • BSubstitution
  • CElimination
  • DHydrolysis
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Correct Answer: Option A — Addition
Explanation: Addition reactions involve adding molecules across the carbon to carbon double bond of an alkene such as the decolourisation of bromine water used as a test for unsaturation.
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74
Chemistry Medium

What is formed when an alcohol reacts with a carboxylic acid?

  • AEster and water
  • BSalt and water
  • CSoap
  • DAlkene and water
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Correct Answer: Option A — Ester and water
Explanation: When an alcohol reacts with a carboxylic acid an esterification reaction occurs producing an ester and water and this reaction requires an acid catalyst such as concentrated sulfuric acid.
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75
Chemistry Medium

Which organic functional group is present in carboxylic acids?

  • AHydroxyl group
  • BCarboxyl group COOH
  • CCarbonyl group
  • DAmino group
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Correct Answer: Option B — Carboxyl group COOH
Explanation: The carboxyl group COOH is the functional group present in all carboxylic acids and is responsible for their acidic properties as it can donate a proton to a base.
Submitted by: PaperMCQs
76
Chemistry Medium

Which organic functional group is present in alcohols?

  • ACarbonyl group
  • BHydroxyl group
  • CCarboxyl group
  • DAmino group
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Correct Answer: Option B — Hydroxyl group
Explanation: The hydroxyl group OH is the functional group present in all alcohols and is responsible for their characteristic properties such as being able to form hydrogen bonds with water.
Submitted by: PaperMCQs
77
Chemistry Medium

What is the role of a catalyst in a chemical reaction?

  • AIncreases activation energy
  • BIs consumed by the reaction
  • CChanges the products formed
  • DIncreases reaction rate without being consumed
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Correct Answer: Option D — Increases reaction rate without being consumed
Explanation: A catalyst increases the rate of a chemical reaction by providing an alternative reaction pathway with lower activation energy and is not consumed or permanently changed during the process.
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78
Chemistry Medium

Which type of chemical formula shows the simplest whole number ratio of atoms in a compound?

  • AMolecular formula
  • BStructural formula
  • CDisplayed formula
  • DEmpirical formula
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Correct Answer: Option D — Empirical formula
Explanation: An empirical formula shows the simplest whole number ratio of each type of atom in a compound for example glucose C6H12O6 has the empirical formula CH2O.
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79
Chemistry Medium

What is the concentration of a solution measured in moles per litre called?

  • ANormality
  • BMolality
  • CFormality
  • DMolarity
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Correct Answer: Option D — Molarity
Explanation: Molarity is the measure of concentration of a solution expressed as the number of moles of solute dissolved per litre of solution with units of mol/L or M.
Submitted by: PaperMCQs
80
Chemistry Medium

Which scientific law states that equal volumes of all gases at the same temperature and pressure contain equal numbers of molecules?

  • ABoyle's Law
  • BGay-Lussac's Law
  • CAvogadro's Law
  • DCharles's Law
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Correct Answer: Option C — Avogadro's Law
Explanation: Avogadro's Law states that equal volumes of all gases at the same temperature and pressure contain equal numbers of molecules regardless of the nature of the gas.
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