The volume of an air bubble becomes three times as it rises from the bottom of a lake to its surface. Assuming atmospheric pressure to be $75\, cm$ of $Hg$ and the density of water to be $1/10$ of the density of mercury,the depth of the lake is ....... $m$.

In a fission reaction ${}_{92}^{236}U \to {}^{117}X + {}^{117}Y + n + n,$ the binding energy per nucleon of $X$ and $Y$ is $8.5\, MeV$ whereas that of ${}^{236}U$ is $7.6\, MeV$. The total energy liberated will be about:

Human urine is usually acidic because:

The modern man differs from the apes in

Two cells $E_1$ and $E_2$ having equal e.m.f '$E$' and internal resistances $r_1$ and $r_2$ $(r_1 > r_2)$ respectively are connected in series. This combination is connected to an external resistance '$R$'. It is observed that the potential difference across the cell $E_1$ becomes zero. The value of $R$ will be

From a disc of radius $R$ and mass $M$,a circular hole of diameter $R$,whose rim passes through the centre is cut. What is the moment of inertia of the remaining part of the disc about a perpendicular axis,passing through the centre?