Explanation

Transistors act as switches and amplifiers, making them essential in audio/video recorders, TVs, computers, and radios.

They are the building blocks of modern electronic circuits.

Explanation

The uranium isotope used in nuclear reactions is 92 U-235. 

Uranium-235 is a fissile isotope, meaning it can undergo nuclear fission when struck by a neutron,

Releasing energy and more neutrons to sustain a chain reaction.

While Uranium-238 is the most abundant isotope of uranium,

It is not fissile and requires a more complex process to be utilized in nuclear reactions. 

Explanation

Internal combustion engines generally use liquid fuels (like petrol, diesel) or gaseous fuels (like CNG, LPG).

Solid fuels are not suitable because they cannot be efficiently injected and combusted inside the engine cylinder.

Explanation

Specific heat capacity is the amount of heat required to raise the temperature of 1 unit mass of a substance by 1°C (or 1 K).

Hence, it is defined per unit mass of the material.

Explanation

Humidity is the measure of the concentration of water vapor in the atmosphere.

Dew, mist, and fog are results of condensation, not the amount of vapor itself.

Explanation

An ammeter is an instrument used to measure small electric current in a circuit.

It typically measures current in amperes (A).

It is connected in series with the circuit.

The potentiometer is used to measure emf.

A meter bridge is used to measure the electrical resistance.

Explanation

When iron is magnetized, the alignment of magnetic domains causes a slight increase in length (called magnetostriction).

The change is very small but measurable.

Explanation

Lead is commonly used as a shield against gamma rays.

Due to its high density.

It effectively absorbs and blocks gamma radiation.

Explanation

Rainwater is formed through evaporation and condensation, a natural distillation process that leaves most impurities and salts behind.

This process effectively purifies the water, making it the purest form found in nature.

Explanation

A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters.

A nautical mile equals 1.852 km.

It is used in air and sea travel.

It is based on the Earth’s circumference, making it ideal for navigation.