All Free Everyday Science MCQs with Answers

1671. Balloons are filled with _________ ?

• A. Nitrogen
• B. Helium
• C. Oxygen
• D. Argon

Explanation: Helium is used in balloons because it is less dense than air and is non-flammable. Hydrogen also provides lift, but its high flammability makes it unsafe for ordinary balloons.

1672. In radiation, which of the following has strong photons?

• A. X-Rays
• B. Gamma
• C. Microwave
• D. Electromagnetic

Explanation: Gamma rays have the highest frequency and photon energy among the listed radiation types, so they are more penetrating than X-rays, microwaves and visible electromagnetic radiation. Photon energy increases with frequency.

1673. Speed of sound in air is _______km/h?

• A. 1347
• B. 243
• C. 1235
• D. 1495

Explanation: Sound travels through air at about 343 metres per second at room temperature. Multiplying by 3.6 converts this to approximately 1,235 kilometres per hour.

1674. A force applied on a body through the string is called_________?

• A. Weight
• B. Momentum
• C. Tension
• D. Torque

Explanation: The pulling force transmitted through a string, rope, or cable is called tension. Weight is gravitational force, while momentum describes motion and torque describes a turning effect.

1675. Which of the following is solid?

• A. Water
• B. Stone
• C. Both
• D. None

Explanation: In the ordinary meaning used here, water is a liquid, whereas stone retains a definite shape and volume and is a solid. Water can become solid as ice, but that is not what the option normally denotes.

1676. Gravitation force of earth is___________?

• A. 9.80 m/s²
• B. 7.21 m/s²
• C. 1.62 m/s²
• D. None of these

Explanation: The acceleration produced by Earth's gravity near its surface is about 9.8 m/s². Strictly speaking, this value is gravitational acceleration rather than a force, so the question uses “force” imprecisely.

1677. The best conductor of heat among liquid is___________?

• A. Water
• B. Mercury
• C. Ether
• D. Alcohol

Explanation: Mercury conducts heat better than the other listed liquids and is also useful in thermometers because it expands predictably with temperature. Water, ether, and alcohol are poorer thermal conductors.

1678. What is the wavelength of visible spectrum:

• A. 1300-3000A
• B. 3900-7600A
• C. 7800-8000A
• D. None of these

Explanation: Visible light has wavelengths of approximately 3900 to 7600 angstroms, equivalent to about 390 to 760 nanometres. Ultraviolet lies below this range and infrared lies above it.

1679. Sound of frequency below 20 Hz is:___________?

• A. Audiosonic
• B. Infrasonic
• C. Ultrasonic
• D. Supersonic

Explanation: Infrasonic sound has a frequency below 20 hertz, below the lower limit of normal human hearing. Ultrasonic sound is above about 20,000 hertz.

1680. Mach number is used in connection with the speed of___________?

• A. Ship
• B. Light
• C. Sound
• D. aircraft

Explanation: Mach number compares an object's speed with the local speed of sound and is commonly used to describe aircraft speed. Mach 1 means travelling at the speed of sound.