The ratio of the total energy of the $2^{\text{nd}}$ orbit electron for the hydrogen atom $1H^1$ to that of the helium ion $(He^{+})$ $2He^4$ is:

Two identical capacitors have the same capacitance $C$. One of them is charged to potential $V_1$ and the other to $V_2$. The negative ends of the capacitors are connected together. When the positive ends are also connected,the decrease in energy of the combined system is

In the adjacent circuit,a voltmeter of internal resistance $R$,when connected across $B$ and $C$,reads $\frac{100}{3} \text{ V}$. Neglecting the internal resistance of the battery,the value of $R$ is

Fresnel diffraction is produced due to light rays falling on a small obstacle. The intensity of light at a point on a screen beyond an obstacle depends on

In humans,which disorder is caused due to the absence of one of the $X$ chromosomes,i.e.,$45$ with $XO$?

When a large bubble rises from the bottom of a lake to the surface, its radius doubles. If atmospheric pressure is equal to that of a column of water of height $H$, then the depth of the lake is: