Control rods used in nuclear reactors are made of:

The number of neutrons released when ${}_{92}^{235}U$ undergoes fission by absorbing ${}_{0}^{1}n$ and products ${}_{56}^{144}Ba$ and ${}_{36}^{89}Kr$ are formed,is:

Match the following items in Column-$A$ with their corresponding principles in Column-$B$:

Column-$A$	Column-$B$
$A$. Rocket propulsion	$P$. Bernoulli's principle in fluid dynamics
$B$. Aeroplane	$Q$. Total internal reflection of light
$C$. Optical fibres	$R$. Newton's laws of motion
$D$. Fusion test reactor	$S$. Magnetic confinement of plasma
	$T$. Photoelectric effect

The atomic power station at Tarapore has a generating capacity of $200\, MW$. The energy generated in a day by this station is:

$A$ $\pi^0$ meson at rest decays into $2$ $\gamma$ rays: $\pi^0 \to \gamma + \gamma$. Which of the following must happen?

In nuclear fission,the percentage of mass converted into energy is about: (in $\%$)