Which of the following statements is wrong?

Which of the following is a longitudinal wave?

The depth of the sea is measured by means of an echo. If the time between the moment the sound is produced and received is $3.52 \,s$, then the depth of the sea is (The compressibility of sea water is $4.84 \times 10^{-10} \,m^2 \,N^{-1}$ and its density is $1024 \,kg \,m^{-3}$): (in $km$)

Which of the following statements are wrong about the velocity of sound in air?

The densities of two diatomic gases at constant temperature and pressure are $d_1$ and $d_2$. The ratio of the speed of sound in these gases is:

It takes $2.0 \ s$ for a sound wave to travel between two fixed points when the day temperature is $10^{\circ}C$. If the temperature rises to $30^{\circ}C$,the sound wave travels between the same fixed points in ...... $s$.