Which one of the following is heterosporous?

The mass defect in a particular nuclear reaction is $0.3 ~g$. The amount of energy liberated in kilowatt hour is: (Velocity of light $= 3 \times 10^8 ~m/s$)

The cathode of a photoelectric cell is changed from a work function $W_1$ to $W_2$ $(W_2 > W_1)$. If the photoelectric currents before and after the change are $I_1$ and $I_2$ respectively,and all other conditions remain constant,then which of the following is true? (Assume $hv > W_2$)

$A$ tank is filled up to a height $h$ with a liquid and is placed on a platform of height $h$ from the ground. To get the maximum range $x_m$,a small hole is punched at a distance of $y$ from the free surface of the liquid. Then:

The ascent of xylem sap in plants is mainly accomplished by the:

Among the nitrates of alkali metals,which one can be decomposed to its oxide on strong heating?