What is the hybridization state of the central atom in the conjugate base of $NH_4^{+}$ ion?

Chemically,borax is:

An element reacts with hydrogen to form a compound $A$ which on treatment with water liberates hydrogen gas. The element can be

If $f(x) = \sin x + \cos x$,then $f\left(\frac{\pi}{4}\right) f^{(iv)}\left(\frac{\pi}{4}\right)$ is equal to

$A$ thin liquid film formed between a $U$-shaped wire and a light slider supports a weight of $1.5 \times 10^{-2} \, N$ (see figure). The length of the slider is $30 \, cm$ and its weight is negligible. The surface tension of the liquid film is (in $, N/m$)

The bond length of $HCl$ molecule is $1.275 \ \mathring{A}$ and its dipole moment is $1.03 \ D$. The ionic character of the molecule (in percent) (charge of the electron $= 4.8 \times 10^{-10} \ esu$) is