In the proton-proton cycle in the Sun,the energy released when an electron and its antiparticle combine is $\qquad$ .

The nuclear reaction $^2H + ^2H \to ^4He$ (mass of deuteron $= 2.0141 \,amu$ and mass of $He = 4.0024 \,amu$) is

Nuclear fusion is common to the pair:

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 binding energy of deuteron $_1^2H$ is $1.112 \, MeV$ per nucleon and an $\alpha$-particle $_2^4He$ has a binding energy of $7.047 \, MeV$ per nucleon. Then in the fusion reaction $_1^2H + _1^2H \to _2^4He + Q$,the energy $Q$ released is ........ $MeV$.

In a nuclear fission reaction of an isotope of mass $M$,three similar daughter nuclei of the same mass are formed. The speed of a daughter nucleus in terms of mass defect $\Delta M$ will be: