One energy difference between the states $n = 2$ and $n = 3$ is $E \, eV$ in a hydrogen atom. The ionization potential of the $H$ atom is ........... $E$.

If a gas expands at constant temperature,it indicates that

If $f:[-6,6] \rightarrow R$ is defined by $f(x)=x^2-3$ for $x \in R$,then $(f \circ f \circ f)(-1)+(f \circ f \circ f)(0)+(f \circ f \circ f)(1)$ is equal to

Two identical flutes produce fundamental notes of frequency $300 \ Hz$ at $27^{\circ}C.$ If the temperature of air in one flute is increased to $31^{\circ}C,$ the number of beats heard per second will be

The products formed when heavy water is reacted with magnesium nitride are:

One end of a string of length $l$ is connected to a particle of mass $m$ and the other to a small peg on a smooth horizontal table. If the particle moves in a circle with speed $v$ and $T$ is the tension in the string,then the net force on the particle (directed towards the centre) is