Why can we not have a conversation on the surface of the Moon?

$A$ plane wave of sound traveling in air is incident upon a plane surface of a liquid. The angle of incidence is $60^{\circ}$. The speed of sound in air is $300 \ m/s$ and in the liquid it is $600 \ m/s$. Assume Snell's law to be valid for sound waves.

Two monoatomic ideal gases $1$ and $2$ of molecular masses $m_1$ and $m_2$ respectively are enclosed in separate containers kept at the same temperature. The ratio of the speed of sound in gas $1$ to that in gas $2$ is given by

The figure represents the instantaneous displacement-position graph of a longitudinal harmonic wave travelling along the negative $x$-axis. Identify the points of maximum compression.

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: $A$ sound wave has higher speed in solids than gases.
Reason $R$: Gases have higher value of Bulk modulus than solids.
In the light of the above statements,choose the correct answer from the options given below:

Mention the type of ultrasonic waves and their frequency.