On average,how many neutrons are released from the fission of a single $U^{235}$ nucleus?

In the options given below, let $E$ denote the rest mass energy of a nucleus and $n$ a neutron. The correct option is:

The most suitable element for nuclear fission is the element with an atomic number near

$A$ nucleus of mass $M + \Delta m$ at rest decays into two daughter nuclei of equal mass $M/2$. If the speed of light is $c$,the speed of each daughter nucleus is:

What is the energy released in the process $3 \, _{2}^{4}\text{He} \to _{6}^{12}\text{C}$ (in $, \text{MeV}$)? (Mass of $_{2}^{4}\text{He} = 4.002604 \, \text{amu}$,mass of $_{6}^{12}\text{C} = 12 \, \text{amu}$)

Suppose a ${ }_{88}^{226} Ra$ nucleus at rest and in the ground state undergoes $\alpha$-decay to a ${ }_{86}^{222} Rn$ nucleus in its excited state. The kinetic energy of the emitted $\alpha$ particle is found to be $4.44 \text{ MeV}$. The ${ }_{86}^{222} Rn$ nucleus then goes to its ground state by $\gamma$-decay. The energy of the emitted $\gamma$-photon is . . . . . . . $\text{keV}$.
[Given: atomic mass of ${ }_{88}^{226} Ra = 226.005 \text{ u}$,atomic mass of ${ }_{86}^{222} Rn = 222.000 \text{ u}$,atomic mass of $\alpha$ particle $= 4.000 \text{ u}$,$1 \text{ u} = 931 \text{ MeV}/c^2$]