In an experiment with a beam balance,an unknown mass $m$ is balanced by two known masses of $16\,kg$ and $4\,kg$ as shown in the figure. The value of the unknown mass $m$ is ......... $kg$.

Two tuning forks $A$ and $B$ produce $8\ Hz$ beats per second when sounded together. $A$ gas column $37.5\ cm$ long in a pipe closed at one end resonates in its fundamental mode with fork $A$,whereas a column of length $38.5\ cm$ of the same gas in a similar pipe is required for a similar resonance with fork $B$. The frequencies of these two tuning forks are:

If $(2,-1,3)$ is the foot of the perpendicular drawn from the origin to the plane, then the equation of the plane is

Reduction in vascular tissue,mechanical tissue,and cuticle is a characteristic of ..........

Which type of mouthparts is present on the lateral side of the pre-oral cavity in cockroach?

When $10 \ g$ of methane is completely burnt in oxygen,the heat evolved is $560 \ kJ$. What is the heat of combustion (in $kJ \ mol^{-1}$) of methane?