$A$ ball at rest is dropped from a height of $12 ~m$. It loses $25 \%$ of its kinetic energy on striking the ground and bounces back to a height '$h$'. Then the value of '$h$' is: (in $~m$)

Identify $A$ and $B$ in the following reaction:
$CH_3-CH_3 \xleftarrow{B} CH_3COOH \xrightarrow{A} CH_3CH_2OH$

$A$

$B$

Find out the major product of the following reaction:
$2 \text{ mole } CH_2=CH-CH_2Br \xrightarrow{Mg, T.H.F}$

$H_3BO_3$ is

$A$ circle passes through the point $(3, 4)$ and cuts the circle $x^2 + y^2 = a^2$ orthogonally. The locus of its centre is a straight line. If the distance of this straight line from the origin is $25$,then $a^2$ is equal to

In a potentiometer experiment,the balancing length with a cell is $240\,cm$. On shunting the cell with a resistance of $2\,\Omega$,the balancing length becomes $120\,cm$. The internal resistance of the cell is ................... $\Omega$.