The electronic configurations of four elements are given as:
$(I) 1s^2, (II) 1s^2 2s^2 2p^2, (III) 1s^2 2s^2 2p^5, (IV) 1s^2 2s^2 2p^6$. Which configuration has the ability to form both ionic and covalent bonds?

$A$ weak acid $HX$ has the dissociation constant $1 \times 10^{-5} \ M$. It forms a salt $NaX$ on reaction with alkali. The percentage hydrolysis of $0.1 \ M$ solution of $NaX$ is ........ $\%$.

In the circuit shown in the figure,the potential difference between points $A$ and $B$ is $16 \, V$. The current passing through the $2 \, \Omega$ resistance will be ................. $A$.

$A$ magnetized wire of magnetic moment $M$ and length $l$ is bent into the form of a semicircle of radius $r$. Then its new magnetic moment is:

The existence of a substance in more than one solid modification is known as:

When a big drop of water is formed from $n$ small drops of water,the energy loss is $3E$,where $E$ is the energy of the bigger drop. If $R$ is the radius of the bigger drop and $r$ is the radius of the smaller drop,then the number of smaller drops $(n)$ is: