41. A sudden flow of charges along with a bright flash of light is called:
(A) Thunder
(B) Thunderstorm
(C) Hailstorm
(D) Lightning
Answer:
(D) Lightning
Explanation:
Lightning is a naturally occurring electrostatic discharge (sudden flow of charges) through the atmosphere, which visibly presents as a bright flash of light. (Thunder is the sound it creates).
42. A specific temperature at which a solid changes state into a liquid state is called:
(A) Melting point
(B) Boiling point
(C) Conversion
(D) Condensation
Answer:
(A) Melting point
Explanation:
In thermodynamics, the melting point of a substance is the exact temperature at which it changes its physical state from a solid to a liquid.
43. Which among the following does not have a fixed shape but has a fixed volume?
(A) Nitrogen
(B) Plastic
(C) Petrol
(D) Gold
Answer:
(C) Petrol
Explanation:
This describes the properties of a liquid. Liquids (like petrol) have a fixed volume but conform to the shape of their container. Solids (plastic, gold) have a fixed shape, and gases (nitrogen) have neither a fixed shape nor volume.
44. In the context of air pollution, the term SPM stands for:
(A) Suspended Particles of Matter
(B) Suspended Particulate Matter
(C) Scanning Probe Microscopy
(D) Sales Performance Management
Answer:
(B) Suspended Particulate Matter
Explanation:
In environmental science, SPM stands for Suspended Particulate Matter, which refers to finely divided solid or liquid particles dispersed in the air that pose health hazards.
45. Air as a homogeneous mixture does not contain:
(A) Nitrogen
(B) Argon
(C) Lithium
(D) Water Vapor
Answer:
(C) Lithium
Explanation:
Air is a mixture primarily composed of nitrogen, oxygen, argon, trace gases, and water vapor. Lithium is a solid alkali metal and is not a natural gaseous component of the Earth’s atmosphere.
