Sonar makes use of:

1. Infrasonic sound
2. Ultrasound
3. Supersonic sound
4. Light

Assertion (A) : Sound waves cannot travel through vacuum.

Reason (R) : Sound travels in the form of longitudinal waves.

1. both A and R are true and R is the correct explanation of A
2. both A and R are true and R is not the correct explanation of A
3. assertion is false but reason is true
4. assertion is true but reason is false

Assertion (A) : Sound travels faster in humid air than in dry air.

Reason (R) : The increase of moisture in air tends to decrease the density of air.

1. both A and R are true and R is the correct explanation of A
2. both A and R are true and R is not the correct explanation of A
3. assertion is false but reason is true
4. assertion is true but reason is false

Assertion (A) : Two persons on the surface of moon can not talk to each other.

Reason (R) : The speed of sound decreases with the decrease in temperature.

1. both A and R are true and R is the correct explanation of A
2. both A and R are true and R is not the correct explanation of A
3. assertion is false but reason is true
4. assertion is true but reason is false