Chemistry Mock Test
Q. What is ‘Dry Ice’?
A) Solid CO₂ B) Solid O₂ C) Solid H₂ D) Solid N₂
Ans: A) Solid CO₂
Explanation: Dry ice is solid carbon dioxide; sublimates directly into CO₂ gas at −78.5°C without melting into liquid.
Q. Most abundant gas in the atmosphere?
A) Oxygen B) Nitrogen C) Carbon dioxide D) Argon
Ans: B) Nitrogen
Explanation: Nitrogen (~78%) dominates air; essential for plant growth and forms the major part of Earth’s atmosphere.
Q. Gas dissolved in soda water ?
A) Oxygen B) Nitrogen C) Carbon dioxide D) Helium
Ans: C) Carbon dioxide
Explanation: CO₂ under pressure dissolves in soda water, producing fizz and slightly acidic taste.
Q. Process of turning milk into curd ?
A) Coagulation B) Fermentation C) Oxidation D) Digestion
Ans: B) Fermentation
Explanation: Lactic acid bacteria ferment lactose into lactic acid, thickening milk into curd.
Q. Brass is an alloy of ?
A) Copper + Tin B) Copper + Zinc C) Copper + Lead D) Iron + Carbon
Ans: B) Copper + Zinc
Explanation: Brass is copper-zinc alloy, used in musical instruments and decorative items.
Q. Lightest metal ?
A) Sodium B) Lithium C) Aluminium D) Potassium
Ans: B) Lithium
Explanation: Lithium is the lightest metal; low density, widely used in batteries and alloys.
Q. Pencil tip is made of ?
A) Coal B) Graphite C) Lead D) Carbon black
Ans: B) Graphite
Explanation: Pencil tips use graphite, whose layered structure leaves marks on paper.
Q. Gas absorbed by green plants ?
A) Oxygen B) Nitrogen C) Carbon dioxide D) Hydrogen
Ans: C) Carbon dioxide
Explanation: CO₂ is absorbed for photosynthesis to produce glucose and oxygen.
Q. Gas absent in dry air ?
A) Nitrogen B) Oxygen C) Carbon dioxide D) Water vapor
Ans: D) Water vapor
Explanation: Dry air lacks water vapor; humidity adds it to the atmosphere.
Q. Chemical name of Bleaching Powder ?
A) CaCO₃ B) CaOCl₂ C) CaCl₂ D) Ca(OH)₂
Ans: B) CaOCl₂
Explanation: Calcium oxychloride disinfects water and bleaches fabrics.
Q. Used to purify drinking water ?
A) Ozone B) Chlorine C) Carbon dioxide D) Nitrogen
Ans: B) Chlorine
Explanation: Chlorine kills harmful microorganisms, making water safe to drink.
Q. Acid present in vinegar ?
A) Hydrochloric B) Acetic C) Sulfuric D) Nitric
Ans: B) Acetic
Explanation: Vinegar contains acetic acid (CH₃COOH) giving sour taste and preservative properties.
Q. Greenhouse effect is caused by ?
A) Nitrogen B) Carbon dioxide C) Oxygen D) Hydrogen
Ans: B) Carbon dioxide
Explanation: CO₂ traps heat in Earth’s atmosphere, leading to greenhouse effect and global warming.
Q. Rusting occurs in which metal ?
A) Copper B) Iron C) Aluminium D) Gold
Ans: B) Iron
Explanation: Iron reacts with oxygen and moisture forming rust (Fe₂O₃·xH₂O), weakening the metal.
Q. ‘Laughing gas’ is ?
A) CO₂ B) N₂O C) O₃ D) SO₂
Ans: B) N₂O
Explanation: Nitrous oxide produces euphoria and is called laughing gas when inhaled.
Q. Which metal is used in making coins ?
A) Iron B) Copper C) Sodium D) Mercury
Ans: B) Copper
Explanation: Durable, corrosion-resistant, easy to shape; ideal for coins.
Q. What is dry ice ?
A) Solid CO₂ B) Frozen nitrogen C) Ice without water D) Mixture of salts
Ans: A) Solid CO₂
Explanation: Dry ice sublimates directly from solid to gas without liquid stage.
Q. Gas used for artificial ripening:
A) CO₂ B) Ethylene C) Oxygen D) Hydrogen
Ans: B) Ethylene
Explanation: Ethylene acts as a ripening hormone for fruits.
Q. Solid to gas conversion:
A) Fusion B) Evaporation C) Condensation D) Sublimation
Ans: D) Sublimation
Explanation: Solid changes directly to gas, e.g., dry ice.
Q. Gas responsible for global warming:
A) Oxygen B) CO₂ C) Nitrogen D) Hydrogen
Ans: B) CO₂
Explanation: Carbon dioxide traps heat in the atmosphere (greenhouse effect).
Q. Element used in pencils:
A) Graphite B) Lead C) Zinc D) Tin
Ans: A) Graphite
Explanation: Pencil “lead” is graphite, a form of carbon.
Q. Acid in vinegar:
A) Citric B) Acetic C) HCl D) H₂SO₄
Ans: B) Acetic acid
Explanation: Vinegar contains 5–8% acetic acid, giving sour taste.
Q. Laughing gas:
A) N₂O B) CO C) Methane D) Hydrogen
Ans: A) Nitrous oxide
Explanation: N₂O causes mild anesthesia and a laughing effect.
Q. Most abundant element:
A) Oxygen B) Hydrogen C) Nitrogen D) Helium
Ans: B) Hydrogen
Explanation: Hydrogen makes up ~75% of the universe by mass.
Q. Metal liquid at room temperature:
A) Sodium B) Iron C) Mercury D) Zinc
Ans: C) Mercury
Explanation: Mercury is the only metal that is liquid at room temperature.
Q. Gas used in fire extinguishers:
A) Oxygen B) CO₂ C) Nitrogen D) Helium
Ans: B) CO₂
Explanation: CO₂ displaces oxygen, extinguishing flames.
Q. Main component of natural gas:
A) Methane B) Ethane C) Propane D) Butane
Ans: A) Methane
Explanation: Natural gas is ~90% methane, used as fuel.
Q. Chemical name of common salt:
A) NaCl B) Sodium carbonate C) KCl D) CaCO₃
Ans: A) Sodium chloride
Explanation: Table salt is chemically sodium chloride.
Q. Material used in safety matches:
A) Phosphorus B) Calcium C) Iron D) Magnesium
Ans: A) Phosphorus
Explanation: Red phosphorus ignites by friction in matches