When temperature increases,the frequency of a tuning fork

Two tuning forks of frequencies $256 \ Hz$ and $258 \ Hz$ are sounded together. The time interval between two consecutive maxima is (in $s$)

$56$ tuning forks are arranged in increasing order of frequencies in a series such that each fork gives $4 \text{ beats per second}$ with the previous one. The frequency of the last fork is the octave of the first. The frequency of the first fork is ..... $Hz$.

Beats are produced by two waves $y_1 = a \sin(1000 \pi t)$ and $y_2 = a \sin(998 \pi t)$. The number of beats heard per second is

$P$ and $Q$ are two wires whose fundamental frequencies are $256 \ Hz$ and $382 \ Hz$ respectively. How many beats per second will be heard if the third harmonic of $P$ and the second harmonic of $Q$ are sounded together?

Two strings $X$ and $Y$ of a sitar produce a beat frequency of $4 \ Hz$. When the tension of the string $Y$ is slightly increased,the beat frequency is found to be $2 \ Hz$. If the frequency of $X$ is $300 \ Hz$,then the original frequency of $Y$ was .... $Hz$.