All Free Everyday Science MCQs with Answers

1511. A lake starts freezing because of the cold atmosphere. It will first freeze

• A. At the bottom
• B. ln the middle pan
• C. At the top surface
• D. Uniformly throughout the water body

Explanation: Water cools from the surface, and the colder, denser water sinks until it reaches about 4°C. Further cooling makes surface water less dense, so ice forms first at the top and then insulates the water below.

1512. Cobalt is a material which is ?

• A. Strongly attracted by a magnet
• B. Not attracted by a magnet
• C. not a magnet
• D. Weakly attracted by a magnet
• E. None of these

Explanation: Cobalt is ferromagnetic, so it is strongly attracted to a magnet and can be magnetised. Iron and nickel show the same important magnetic property.

1513. A body can escape the gravitational pull of the earth if it is thrown up with a velocity of?

• A. 25 miles per sec
• B. 60 miles per sec
• C. 7 miles per sec
• D. 10 miles per sec
• E. None of these

Explanation: Earth's escape velocity is about 11.2 km/s, or approximately 7 miles per second, ignoring air resistance. At this speed, an object can escape Earth's gravitational field without further propulsion.

1514. Magnifying power of a simple microscope can be increased by ?

• A. increasing focal length of the lens
• B. Decreasing focal length of the lens
• C. Lens of large aperture
• D. lens of short aperture
• E. None of these

Explanation: For a simple microscope, magnifying power increases as the focal length decreases, since its angular magnification is approximately proportional to 1/f. Aperture mainly affects brightness and resolving ability, not the basic magnification here.

1515. Cusec is a unit of _________?

• A. Area
• B. Time
• C. Distance
• D. mass
• E. None of these

Explanation: A cusec means one cubic foot per second, so it measures the rate of flow of a fluid. None of the listed choices names a flow-rate unit.

1516. The principle used in radar is the same as that of Sonar. In radar we use radio waves ; whereas in sonar we use ?

• A. red waves
• B. Infrared waves
• C. Ultrasonic
• D. super sonic
• E. None of these

Explanation: Sonar uses ultrasonic sound waves, whose frequencies are above the human hearing range. Radar uses electromagnetic radio waves, so the two systems use different kinds of waves despite similar echo-based principles.

1517. A six feet tall lady wants to see her full image in a plane mirror . The minimum length of the mirror will be ?

• A. 6 feet
• B. 12 feet
• C. 4 feet
• D. 3 feet
• E. None of these

Explanation: A plane mirror only needs to be half as tall as the observer for the observer to see the complete body, because rays from the head and feet reach the mirror at halfway points. For a six-foot person, the minimum mirror length is therefore three feet.

1518. When a ray of sunlight enters a dark room , its straight path become visible because of dust particles hanging in the air. It is because light is _________?

• A. Visible
• B. Transparent
• C. Invisible
• D. opaque
• E. None of these

Explanation: Dust particles scatter visible light into the observer's eyes, making the otherwise invisible path of the beam appear visible. The option 'visible' is the intended choice, although scattering is the actual mechanism.

1519. The echo (reflected sounD. will be distinctly heard only at ordinary temperatures if the distance of the reflecting surfaces from the source of sound is at least ________?

• A. 1120 ft
• B. 120 ft
• C. 56 ft
• D. 100 ft
• E. None of these

Explanation: A distinct echo requires the reflected sound to arrive at least 0.1 second after the direct sound. At about 1120 feet per second, the sound travels 112 feet in that time, so the reflector must be half that distance, or 56 feet, away.

1520. In winter an iron pipe feel colder than a wooden window . This is because wood is_______?

• A. Conductor
• B. Non-Conductor
• C. Semi- Conductor
• D. Not a solid while iron is a solid
• E. None of these

Explanation: Wood is a poor conductor of heat, so it draws heat from the hand more slowly than iron. Iron therefore feels colder even when both materials are at the same temperature.