Question 2 :
Mixing up of air with materials, injurious to health, is termed as:

Question 3 :
1 kg of ________ can light up $1$ bulb for $3\times10^4$ years.

Question 4 :
Which of the following is not a measure of controlling air pollution?

Question 11 :
Let $E_1$ and $E_2$ be the binding energies of two nuclei A and B. It is observed that two nuclei of A combine together to form a B nucleus. This observation is correct only if<br>

Question 12 :
Radium$^{ 226 }{ Ra }$,spontaneously decays to radon with the emission of an $\alpha $-particle and a $\gamma $ ray. If thespeed of the$\alpha $particleupon emission from an initially stationary radium nucleus is$1.5\quad \times \quad { 10 }^{ 7 }\quad m/s$ , what is the recoil speed of the resultant radon nucleus? Assume the momentum of $\gamma $ray is negligible compare to that of$\alpha $particle.

Question 14 :
Among the following which is used in the nuclear reactor as a moderator?<br/>

Question 16 :
In the nuclear reaction given by $_2He^4+_7N^{14}\rightarrow _1H^1+X$ the nucleus X is<br>

Question 17 :
A helium atom, a hydrogen atom and a neutron have masses of $4.003 u$, $1.008 u$ and $1.009 u$ (unified atomic mass units), respectively. Assuming that hydrogen atoms and neutrons can fuse to form helium, what is the binding energy of a helium nucleus?<br>

Question 18 :
Assertion: Heavy nuclides tend to have more number of neutrons than protons. Reason: In heavy nuclei, as there is coloumbic repulsion between protons, so excess of neutrons are preferable.

Question 19 :
At what rate, in mega gram per minute, must hydrogen be consumed in fusion reaction to provide the sun with the energy it radiates? (Take mass defect per reaction to be $0.028706 \,a.m.u$)<br>

Question 20 :
The reaction responsible for the production of light energy from the sun will be: