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CSS MCQs

Civil Superior Services — Complete MCQ Bank

36 Questions
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21
Chemistry Hard

Which synthetic polymer was the first to be produced commercially and is used to make electrical fittings?

  • ANylon
  • BPVC
  • CBakelite
  • DPolythene
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Correct Answer: Option C — Bakelite
Explanation: Bakelite was the first commercially produced synthetic polymer made from phenol and formaldehyde in 1907 and is used in electrical fittings phone casings and kitchenware.
Submitted by: PaperMCQs
22
Chemistry Hard

What is the chemical formula for bleaching powder used in water purification?

  • ACa(OH)2
  • BCaCO3
  • CCa(OCl)Cl
  • DCaCl2
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Correct Answer: Option C — Ca(OCl)Cl
Explanation: Bleaching powder is calcium hypochlorite chloride Ca(OCl)Cl made by passing chlorine gas over slaked lime and used as a disinfectant and bleaching agent.
Submitted by: PaperMCQs
23
Chemistry Medium

What is saponification in chemistry?

  • AMaking soap by reacting fats with a strong alkali
  • BConversion of oils to alcohol
  • CAdding hydrogen to unsaturated fats
  • DMaking esters from acids and alcohols
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Correct Answer: Option A — Making soap by reacting fats with a strong alkali
Explanation: Saponification is the process of making soap by reacting fats or oils with a strong alkali such as sodium hydroxide producing glycerol and soap molecules.
Submitted by: PaperMCQs
24
Chemistry Medium

Which process converts vegetable oils into solid fats by adding hydrogen in the presence of a nickel catalyst?

  • ASaponification
  • BHydrogenation
  • CEsterification
  • DFermentation
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Correct Answer: Option B — Hydrogenation
Explanation: Hydrogenation adds hydrogen gas to unsaturated vegetable oils in the presence of a nickel catalyst converting carbon to carbon double bonds to single bonds producing solid margarine.
Submitted by: PaperMCQs
25
Chemistry Hard

Which type of isomerism involves compounds with the same molecular formula but different structural arrangements?

  • AStructural isomerism
  • BOptical isomerism
  • CGeometric isomerism
  • DDynamic isomerism
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Correct Answer: Option A — Structural isomerism
Explanation: Structural isomers have the same molecular formula but different connectivity of atoms leading to different structural arrangements and distinct physical and chemical properties.
Submitted by: PaperMCQs
26
Chemistry Medium

What does Avogadro's number represent?

  • ANumber of atoms in 1 gram of hydrogen
  • BNumber of particles in one mole of a substance
  • CNumber of molecules in 1 litre of gas
  • DNumber of protons in a nucleus
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Correct Answer: Option B — Number of particles in one mole of a substance
Explanation: Avogadro's number is approximately 6.022 x 10 to the power 23 and represents the number of atoms molecules or ions contained in one mole of any substance.
Submitted by: PaperMCQs
27
Chemistry Hard

Which law states that gases combine in simple whole number ratios by volume at the same temperature and pressure?

  • AGay-Lussac's Law
  • BBoyle's Law
  • CCharles's Law
  • DAvogadro's Law
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Correct Answer: Option A — Gay-Lussac's Law
Explanation: Gay-Lussac's Law of Combining Volumes states that gases react in simple whole number ratios by volume at constant temperature and pressure providing evidence for atomic theory.
Submitted by: PaperMCQs
28
Chemistry Medium

What is the general formula of alkanes where n is the number of carbon atoms?

  • ACnH2n
  • BCnH2n+2
  • CCnHn
  • DCnH2n-2
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Correct Answer: Option B — CnH2n+2
Explanation: Alkanes follow the general formula CnH2n plus 2 where each carbon forms four single bonds and the molecule is fully saturated with hydrogen atoms.
Submitted by: PaperMCQs
29
Chemistry Hard

What are the products of the electrolysis of brine sodium chloride solution?

  • ASodium and water
  • BHydrogen chlorine and sodium hydroxide
  • CChlorine and sodium
  • DSodium chloride and water
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Correct Answer: Option B — Hydrogen chlorine and sodium hydroxide
Explanation: Electrolysis of brine produces hydrogen gas at the cathode chlorine gas at the anode and sodium hydroxide solution remaining in the electrolyte through the chlor-alkali process.
Submitted by: PaperMCQs
30
Chemistry Medium

Which process involves passing an electric current through a solution to cause a chemical reaction?

  • AElectrolysis
  • BDistillation
  • CChromatography
  • DFiltration
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Correct Answer: Option A — Electrolysis
Explanation: Electrolysis passes an electric current through an electrolyte solution or molten ionic compound causing chemical reactions at the electrodes and is used to extract metals and plate surfaces.
Submitted by: PaperMCQs
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