The intensity produced by one source of sound is $30 \mathrm{dB}$. If two such coherent sources are sounded together with zero phase difference, then the intensity level will be

Assertion: When sound wave travels from air to water, it bends towards normal.

Reason: When any wave refracts from rarer to denser medium, it bends towards normal.

Assertion: If temperature is increased, fundamental frequency of an open pipe will increase.

Reason: By increasing the temperature speed of sound wave will increase.

Assertion: In organ pipe experiment, loop size will decrease as the water column length is increased.

Reason: Frequency remains unchanged.

Assertion: In Doppler effect, if the source is moving, change in frequency is observed due to change in wavelength.

Reason: By the motion of source wavelength always decreases.

Assertion: Transverse mechanical wave does not travel in air.

Reason: Air has only bulk modulus of elasticity.

Assertion: A closed pipe and an open pipe cannot be in resonance with the same tuning fork, if the length of the closed pipe is integral multiple of the length of the open pipe.

Reason: An odd number is not divisible by an even number.

Assertion: No Doppler effect will be observed in sound when source and observer are moving with the same speed.

Reason: Doppler effect may be due to change in wavelength also.

Assertion: Ultrasonic is the acoustic analogue of ultraviolet radiation.

Reason: Ultraviolet rays do not produce visual sensations while ultrasonic waves are not heard by the human ear.