$A$ neutron strikes a ${ }_{92}^{235}U$ nucleus and as a result ${ }_{38}^{93}Kr$ and ${ }_{56}^{140}Ba$ are produced along with:

Pick out the correct statements from the following:
$I$. Electron emission during $\beta$-decay is always accompanied by neutrino.
$II$. Nuclear force is charge independent.
$III$. Fusion is the chief source of stellar energy.

An atomic power nuclear reactor can deliver $300\ MW$. The energy released due to fission of each nucleus of uranium atom $^{238}U$ is $170\ MeV$. The number of uranium atoms fissioned per hour will be:

Fast neutrons can easily be slowed down by

Which of the following is a fusion reaction?

When a sample of solid lithium is placed in a flask of hydrogen gas,the following reaction occurs: $_1^1H + {_3^7Li} \to {_2^4He} + {_2^4He}$. This statement is: