All Free Everyday Science MCQs with Answers

1. Deficiency of Vitamin C causes which disease?

• A. Rickets
• B. Scurvy
• C. Beriberi
• D. Night blindness

Explanation: Vitamin C (ascorbic acid) is required for collagen synthesis; its deficiency causes scurvy, marked by bleeding gums and poor wound healing. Rickets is a Vitamin D deficiency, beriberi a Vitamin B1 deficiency, and night blindness a Vitamin A deficiency.

2. What is the normal human body temperature in degrees Celsius?

• A. 35 °C
• B. 37 °C
• C. 39 °C
• D. 41 °C

Explanation: Normal human body temperature is approximately 37 °C, which equals 98.6 °F. Converting between the two uses F = (C × 9/5) + 32, a calculation that itself appears regularly in everyday science sections.

3. Sound cannot travel through which of the following?

• A. Water
• B. Steel
• C. Vacuum
• D. Air

Explanation: Sound is a mechanical wave and requires a material medium whose particles can vibrate. A vacuum contains no particles, so sound cannot propagate through it. This is why astronauts must use radio, which is an electromagnetic wave and needs no medium.

4. The ozone layer is found in which layer of the atmosphere?

• A. Troposphere
• B. Stratosphere
• C. Mesosphere
• D. Thermosphere

Explanation: The ozone layer lies in the stratosphere, roughly 15 to 35 kilometres above the earth, where it absorbs most of the sun’s harmful ultraviolet radiation. The troposphere below it is where weather occurs.

5. What is the chemical name of common table salt?

• A. Sodium bicarbonate
• B. Sodium chloride
• C. Calcium carbonate
• D. Potassium chloride

Explanation: Table salt is sodium chloride, NaCl. Sodium bicarbonate (NaHCO₃) is baking soda and calcium carbonate (CaCO₃) is limestone — both common distractors in everyday science papers.

6. Which planet is closest to the Sun?

• A. Venus
• B. Mercury
• C. Earth
• D. Mars

Explanation: Mercury is the closest planet to the Sun and also the smallest planet in the solar system. Venus is second and is the hottest planet, because its dense carbon dioxide atmosphere traps heat far more effectively than Mercury’s negligible one.

7. In electronics, LED stands for:

• A. Light Emitting Diode
• B. Low Energy Device
• C. Linear Electric Display
• D. Light Enhanced Detector

Explanation: LED stands for Light Emitting Diode — a semiconductor that emits light when current flows through it in the forward direction. LEDs consume far less power than incandescent bulbs, which is why they dominate lighting and display technology.

8. Which blood group is known as the universal donor?

• A. AB positive
• B. A negative
• C. O negative
• D. B positive

Explanation: O negative red cells carry neither A nor B antigens nor the Rh D antigen, so they can be transfused to a recipient of any blood group in an emergency. AB positive is the universal recipient, for the mirror-image reason.

9. Which planet is known for its beautiful rings?

• A. Mars
• B. Jupiter
• C. Saturn
• D. Uranus

Explanation: Saturn is famous for its broad, bright system of icy rings, which makes it the standard answer. Jupiter and Uranus also have rings, but they are much fainter and less prominent.

10. Which month of calendar year can lack a new moon?

• A. December
• B. February
• C. May
• D. None

Explanation: February is short enough that, in some years, its interval contains no new moon. This happens because a lunar cycle is about 29.5 days, longer than February in many years.