The major product of the following reaction is

Why is a solution of potassium hydroxide used to absorb carbon dioxide evolved during the estimation of carbon present in an organic compound?

The modern man differs from the apes in

$A$ beam of electrons is moving with constant velocity in a region having electric and magnetic fields of strength $20 \; Vm^{-1}$ and $0.5 \; T$ at right angles to the direction of motion of the electrons. What is the velocity (in $m/s$) of the electrons?

If the chord of contact of tangents from a point on the circle $x^2 + y^2 = r_1^2$ to the circle $x^2 + y^2 = r_2^2$ touches the circle $x^2 + y^2 = r_3^2$,then $r_1, r_2, r_3$ are in:

$A$ fresh radioactive sample is given at $t = 0$. Its decay fraction is $\frac{1}{5}$ at $t_1$ instant and $\frac{4}{5}$ at $t_2$ instant. Its mean life is