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PPSC MCQs

Punjab Public Service Commission — Complete MCQ Bank

1,262 Questions
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How to prepare for PPSC

PPSC examinations recruit candidates for Punjab government departments and commonly test general knowledge, current affairs, English and post-related subjects.

Punjab AffairsGeneral KnowledgeCurrent AffairsEnglish
Give special attention to Punjab geography, history and administration alongside the advertised post’s specialist syllabus.
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All Subjects Biology Chemistry Computer Science Current Affairs English Everyday Science General Knowledge Islamic Studies Mathematics Pakistan Studies Physics
281
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
282
Chemistry Medium

What is the chemical formula for nitric acid used in fertiliser and explosive manufacturing?

  • AH2SO4
  • BHCl
  • CH3PO4
  • DHNO3
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Correct Answer: Option D — HNO3
Explanation: Nitric acid has the formula HNO3 and is a strong oxidising acid used in the production of fertilisers explosives and in metal etching processes.
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283
Chemistry Medium

Which element is essential for the structure of DNA and RNA molecules alongside carbon hydrogen oxygen and nitrogen?

  • ASulfur
  • BCalcium
  • CIron
  • DPhosphorus
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Correct Answer: Option D — Phosphorus
Explanation: Phosphorus is a key element in DNA and RNA molecules forming the phosphate backbone of the double helix structure and is also essential in ATP the cell's energy currency.
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284
Chemistry Easy

What is the process by which plants use carbon dioxide and water to make glucose using sunlight?

  • ARespiration
  • BTranspiration
  • CPhotosynthesis
  • DDecomposition
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Correct Answer: Option C — Photosynthesis
Explanation: Photosynthesis uses sunlight to convert carbon dioxide and water into glucose and oxygen in the chloroplasts of plant cells following the equation 6CO2 plus 6H2O giving C6H12O6 plus 6O2.
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285
Chemistry Easy

Which noble gas is used in glowing advertising signs giving a reddish-orange colour?

  • AArgon
  • BHelium
  • CNeon
  • DKrypton
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Correct Answer: Option C — Neon
Explanation: Neon gas is used in neon signs and emits a characteristic reddish-orange glow when electricity passes through it due to the excitation of its electrons.
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286
Chemistry Easy

What is the chemical formula for ozone, the molecule that forms the protective layer in the stratosphere?

  • AO
  • BO2
  • CO3
  • DO4
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Correct Answer: Option C — O3
Explanation: Ozone has the chemical formula O3 consisting of three oxygen atoms and forms the stratospheric ozone layer that absorbs harmful UV radiation protecting life on Earth.
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287
Chemistry Medium

Which gas is responsible for the distinctive smell of rotten eggs?

  • AMethane
  • BHydrogen sulfide
  • CAmmonia
  • DSulfur dioxide
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Correct Answer: Option B — Hydrogen sulfide
Explanation: Hydrogen sulfide H2S is a colourless toxic gas responsible for the characteristic smell of rotten eggs and is produced by the bacterial decomposition of organic matter.
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288
Chemistry Easy

What is the chemical name for baking soda commonly used in cooking?

  • ASodium hydroxide
  • BSodium carbonate
  • CSodium chloride
  • DSodium bicarbonate
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Correct Answer: Option D — Sodium bicarbonate
Explanation: Baking soda is sodium bicarbonate NaHCO3 which releases carbon dioxide gas when heated or mixed with acid causing baked goods to rise during cooking.
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289
Chemistry Medium

What is the chemical formula for ethanol the type of alcohol found in beverages?

  • AC2H5OH
  • BCH3OH
  • CC3H7OH
  • DC4H9OH
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Correct Answer: Option A — C2H5OH
Explanation: Ethanol has the chemical formula C2H5OH and is the type of alcohol produced by fermentation of sugars by yeast and is found in alcoholic beverages and used as a solvent.
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290
Chemistry Medium

Which chemical process is used to extract metals from their ores using carbon or electrolysis?

  • AReduction
  • BOxidation
  • CNeutralisation
  • DChromatography
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Correct Answer: Option A — Reduction
Explanation: Reduction is used to extract metals from their ores by removing oxygen using a reducing agent like carbon or by electrolysis for more reactive metals like aluminium.
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