$A$ body of mass $m$ moving with velocity $v$ collides head-on with another body of mass $2m$ which is initially at rest. The ratio of the kinetic energy of the colliding body before and after the collision will be: (in $:1$)

Carbon,silicon,and germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy band gaps represented by $(Eg)_C$,$(Eg)_{Si}$,and $(Eg)_{Ge}$ respectively. Which one of the following relationships is true in their case?

If all the seven letters of the word $LEADING$ are permuted in all possible ways and the words thus formed are arranged as in the dictionary order,then the word in $2017^{\text{th}}$ place is

In the following circuit,find $I_1$ and $I_2$.

If the system of linear equations $x + 2ay + az = 0$,$x + 3by + bz = 0$,and $x + 4cy + cz = 0$ has a non-zero solution,then $a, b, c$:

The presence of a nitro group in a benzene ring.....