When a tuning fork produces sound waves in air,which one of the following remains the same in the material of the tuning fork as well as in the air?

Two tuning forks $A$ and $B$ are sounded together and produce $6$ beats per second. The frequency of tuning fork $B$ is $384 \,Hz$. When tuning fork $A$ is loaded with wax,the number of beats per second becomes $4$. What is the frequency of tuning fork $A$ in $Hz$?

When a tuning fork $A$ of unknown frequency is sounded with another tuning fork $B$ of frequency $256 \ Hz$,then $3$ beats per second are observed. After that,$A$ is loaded with wax and sounded again,and $3$ beats per second are observed. The frequency of the tuning fork $A$ is ..... $Hz$.

Two sound sources,when sounded simultaneously,produce four beats in $0.25 \ s$. The difference in their frequencies must be: (in $Hz$)

Two perfectly identical wires are in unison. When the tension in one wire is increased by $1\%$,then on sounding them together $3$ beats are heard in $2 \,s$. The initial frequency of each wire is .... $\text{s}^{-1}$.

$A$ tuning fork $A$ of frequency $200 \ Hz$ is sounded with fork $B,$ the number of beats per second is $5.$ By putting some wax on $A,$ the number of beats increases to $8.$ The frequency of fork $B$ is .... $Hz$