$A$ concave mirror of focal length $f$ (in air) is immersed in water $(\mu = 4/3)$. The focal length of the mirror in water will be

The reaction of propane with bromine in the presence of $UV$ light predominantly forms

The amplitude of vibration of a particle is given by $a_m = a_0 / (a\omega^2 - b\omega + c)$,where $a_0$,$a$,$b$,and $c$ are positive constants. The condition for a single resonant frequency is:

What is the ratio of the rate of diffusion of oxygen $(O_2)$ and hydrogen $(H_2)$?

In the $Hoop$ process for the refining of $Al$,the molten materials form three different layers and remain separate during electrolysis because ..........

In the ground state,an element has $13$ electrons in the $M$ shell. The element is