Physics & Chemistry Basics Quiz

Question 1

The SI unit of force is:‌​‍

Accepted Answer

Newton — Newton (N) is the SI unit of force. ‌​‍Named after Sir Isaac Newton. 1 N = force to accelerate 1 kg by 1 m/s².

Answer

Joule

Answer

Watt

Answer

Pascal

Question 2

Sound travels fastest in:‌​‍

Accepted Answer

Steel — Sound travels fastest in solids (steel ~5,960 m/s) > liquids (water ~1,480 m/s) > gases (air ~343 m/s). ‌​‍Sound cannot travel through vacuum.

Answer

Vacuum

Answer

Air

Answer

Water

Question 3

The chemical formula of baking soda is:‌​‍

Accepted Answer

NaHCO₃ — Baking soda is Sodium Bicarbonate (NaHCO₃). ‌​‍Washing soda is Na₂CO₃. Common salt is NaCl. ‌​‍Limestone is CaCO₃.

Answer

NaCl

Answer

Na₂CO₃

Answer

CaCO₃

Question 4

The pH of pure water is:‌​‍

Accepted Answer

7 — Pure water has a pH of 7, which is neutral. ‌​‍Below 7 = acidic, above 7 = alkaline.

Answer

0

Answer

5

Answer

14

Question 5

Which metal is liquid at room temperature?‌​‍

Accepted Answer

Mercury — Mercury (Hg) is the only metal that is liquid at room temperature. ‌​‍Bromine is the only non-metal that is liquid at room temperature.

Answer

Lead

Answer

Zinc

Answer

Tin

Question 6

The mirror used as a rear-view mirror in vehicles is:‌​‍

Accepted Answer

Convex mirror — Convex mirrors are used as rear-view mirrors because they provide a wider field of view, allowing drivers to see more of the road behind.‌​‍

Answer

Plane mirror

Answer

Concave mirror

Answer

Parabolic mirror

Question 7

The most abundant element in the Earth's crust is:‌​‍

Accepted Answer

Oxygen — Oxygen is the most abundant element in Earth's crust (~46% by weight), followed by Silicon (~28%), Aluminium (~8%), and Iron (~5%).‌​‍

Answer

Silicon

Answer

Iron

Answer

Aluminium

Question 8

Ohm's Law states that:‌​‍

Accepted Answer

V = IR — Ohm's Law: V = IR (Voltage = Current × Resistance). ‌​‍This is the fundamental law of electricity.

Answer

F = ma

Answer

E = mc²

Answer

P = VI

Question 9

The human hearing range is:‌​‍

Accepted Answer

20-20,000 Hz — Humans can hear sounds in the frequency range of 20 Hz to 20,000 Hz. ‌​‍Below 20 Hz = infrasound. Above 20,000 Hz = ultrasound.

Answer

1-100 Hz

Answer

100-50,000 Hz

Answer

500-100,000 Hz

Question 10

The hardest natural substance is:‌​‍

Accepted Answer

Diamond — Diamond (a crystalline form of carbon) is the hardest known natural substance, scoring 10 on the Mohs hardness scale.‌​‍

Answer

Gold

Answer

Iron

Answer

Platinum

Question 11

Rusting of iron is a process of:‌​‍

Accepted Answer

Oxidation — Rusting is oxidation of iron: Iron + Oxygen + Moisture → Iron Oxide (rust/Fe₂O₃). ‌​‍It requires both oxygen and water.

Answer

Reduction

Answer

Sublimation

Answer

Fermentation

Question 12

Dry ice is the solid form of:‌​‍

Accepted Answer

Carbon Dioxide — Dry ice is solid Carbon Dioxide (CO₂). ‌​‍It sublimes directly from solid to gas at -78.5°C, without passing through a liquid phase.

Answer

Oxygen

Answer

Nitrogen

Answer

Water

Question 13

The gas used in fire extinguishers is:‌​‍

Accepted Answer

Carbon Dioxide — Carbon Dioxide (CO₂) is used in fire extinguishers because it is heavier than air, non-combustible, and smothers the fire by cutting off oxygen supply.‌​‍

Answer

Oxygen

Answer

Hydrogen

Answer

Nitrogen

Question 14

The speed of light in vacuum is approximately:‌​‍

Accepted Answer

3 × 10⁸ m/s — The speed of light in vacuum is approximately 3 × 10⁸ metres per second (about 300,000 km/s). ‌​‍Nothing can travel faster than light.

Answer

3 × 10⁶ m/s

Answer

3 × 10¹⁰ m/s

Answer

3 × 10⁴ m/s

Question 15

Laughing gas is:‌​‍

Accepted Answer

Nitrous Oxide (N₂O) — Nitrous Oxide (N₂O) is called laughing gas. ‌​‍It is used as an anaesthetic in dentistry and surgery. It causes a feeling of euphoria when inhaled.

Answer

Carbon Monoxide (CO)

Answer

Carbon Dioxide (CO₂)

Answer

Nitric Oxide (NO)

Physics & Chemistry Basics Quiz