The $pK_a$ of a weak acid $HA$ is $4.5$. The $pOH$ of an aqueous buffered solution of $HA$ in which $50\%$ of the $HA$ acid is ionized is

In humans,at the end of the first meiotic division,the male germ cells differentiate into the

$\int_{-1}^1 (a x^3 + b x) d x = 0$ for

The maximum value of $\sin (\cos (\tan x))$ is

Which of the following forms a colloidal solution in water?

$A$ light wave is incident normally on a slit of width $24 \times 10^{-5} \ cm$. The angular position of the second dark fringe from the central maxima is $30^{\circ}$. What is the wavelength of light in $\mathring{A}$?