Which of the following is the most toxic pesticide for vertebrates?

$A$ monoatomic ideal gas,initially at temperature $T_1$,is enclosed in a cylinder fitted with a frictionless piston. The gas is allowed to expand adiabatically to a temperature $T_2$ by releasing the piston suddenly. If $L_1$ and $L_2$ are the lengths of the gas column before and after expansion respectively,then $\frac{T_1}{T_2}$ is given by:

What is the catalyst used in the conversion of acetaldehyde to acetic acid?

On heating,which of the following releases $CO_2$ most easily?

The technique used to make numerous copies of a specific segment of $DNA$ quickly and accurately is

If the angles of a triangle are in the ratio $4:1:1,$ then the ratio of the longest side to the perimeter is