Which property distinguishes progressive waves from stationary waves?

The intensity of sound from a radio at a distance of $2 \ m$ from its speaker is $1 \times 10^{-2} \ \mu W/m^2$. The intensity at a distance of $10 \ m$ would be:

The intensity level at a distance of $200 \ cm$ from a sound source is $80 \ dB$. If there is no loss of acoustic power in the air and the threshold intensity of hearing is $10^{-12} \ W/m^2$,what is the intensity level at a distance of $400 \ cm$ from the source (in $dB$)?

$A$ stationary point source of sound emits sound uniformly in all directions in a non-absorbing medium. Two points $P$ and $Q$ are at a distance of $4 \ m$ and $9 \ m$ respectively from the source. The ratio of amplitudes of the waves at $P$ and $Q$ is

On getting reflected at a surface,the intensity of sound is found to be decreased by $20 \%$. If $A$ be the amplitude of the incident sound waves,then the amplitude of reflected sound waves is

If the ratio of intensities of two waves is $1 : 25$,then the ratio of their amplitudes will be