All Free Everyday Science MCQs with Answers

321. Laughing gas has chemical composition of following two elements ?

• A. Nitrogen + Hydrogen
• B. Nitrogen + Carbon
• C. Nitrogen + Oxygen
• D. Oxygen + Carbon
• E. None of these

Explanation: Laughing gas is nitrous oxide, N₂O, so it contains nitrogen and oxygen. Its name refers to its temporary euphoric effects when inhaled, not to its chemical composition.

322. Which woody raw material is used for the manufacture of paper pulp?

• A. Cotton
• B. Poplar
• C. Bagasse
• D. Rice straw

Explanation: Poplar is a woody tree whose wood is processed into pulp for papermaking. Cotton, bagasse and rice straw are fibrous non-woody raw materials rather than woody material.

323. Rectified spirit contains alcohol about ?

• A. 80%
• B. 95%
• C. 70%
• D. 85%Exploring Online Chemistry Courses

Explanation: Rectified spirit is highly purified ethanol obtained by repeated distillation and typically contains about 95% alcohol by volume. It is not completely pure because ethanol and water form an azeotropic mixture.

324. Bronze medal is made up of metals ?

• A. copper,nickel
• B. copper, tin
• C. copper, silver
• D. copper, zinc

Explanation: Bronze is traditionally an alloy of copper and tin, valued for its hardness and corrosion resistance. Copper and zinc form brass, which is the common alternative trap.

325. The three elements needed for healthy growth of plants are __________?

• A. N, P, K
• B. N, C, P
• C. N, K,
• D. N, S, P

Explanation: Nitrogen, phosphorus and potassium are the three primary macronutrients required by plants. They support leafy growth, roots and reproduction, and overall water and enzyme regulation respectively.

326. The fourth state of matter is?

• A. Water
• B. Salts
• C. Vapours
• D. Plasma

Explanation: Plasma is an ionised gas containing free electrons and ions, and it behaves differently from solids, liquids and ordinary gases. Lightning, neon signs and stars contain plasma.

327. The natural fats and oils are composed of_________?

• A. Carbon, Hydrogen and Oxygen
• B. Carbon, Hydrogen and Nitrogen
• C. Carbon, Oxygen and Nitrogen
• D. Hydrogen, Oxygen and Nitrogen

Explanation: Natural fats and oils are mainly triglycerides, whose molecules contain carbon, hydrogen and oxygen. Nitrogen is not a basic element of ordinary triglycerides.

328. The gas, commonly known as "laughing gas", is

• A. Carbon Dioxide
• B. Sulfur Dioxide
• C. Nitrous Oxide
• D. Sodium Oxide

Explanation: Nitrous oxide, N2O, is called laughing gas and has been used as an inhaled anaesthetic and analgesic. It is different from nitrogen dioxide, a toxic brown atmospheric pollutant.

329. Diamond is an allotropic form of_______?

• A. Carbon
• B. Hydrogen
• C. Nitrogen
• D. Silicon

Explanation: Diamond is an allotrope of carbon, meaning it is a different structural form of the same element. Graphite and graphene are other well-known carbon allotropes.

330. What is Dry Ice?

• A. Solid Oxygen
• B. Solid Carbon Dioxide
• C. Solid Hydrogen
• D. Solid Nitrogen

Explanation: Dry ice is carbon dioxide in its solid state. It changes directly into gas by sublimation instead of melting into a liquid at normal pressure.