The sun radiates energy in all directions. The average radiations received on the earth surface from the sun is 1.4 $\mathrm{kilowatt}/{\mathrm{m}}^2$.The average earth- sun distance is $1.5\times {10}^{11}$ metres. The mass lost by the sun per day is
(1 day = 86400 seconds) 
(a) $4.4\times {10}^9 \mathrm{kg}$          (b) $7.6\times {10}^{14} \mathrm{kg}$
(c) $3.8\times {10}^{12} \mathrm{kg}$         (d) $3.8\times {10}^{14} \mathrm{kg}$

The binding energy per nucleon of ${\mathrm{O}}^{16}$ is 7.97 MeV and that of ${\mathrm{O}}^{17}$ is 7.75 MeV. The energy (in MeV) required to remove a neutron from ${\mathrm{O}}^{17}$ is 
(a) 3.52                 (b) 3.64
(c) 4.23                 (d) 7.86

The rest energy of an electron is 0.511 MeV. The electron is accelerated from rest to a velocity 0.5 c. The change in its energy will be
(1) 0.026 MeV           

(2) 0.051 MeV

(3) 0.079 MeV           

(4) 0.105 MeV

For uranium nucleus how does its mass vary with volume

(1) $\mathrm{m}\propto \mathrm{V}$          

(2) $\mathrm{m}\propto 1/\mathrm{V}$

(3) $\mathrm{m}\propto \sqrt{\mathrm{V}}$       

(4) $\mathrm{m}\propto {\mathrm{V}}^2$

In the nuclear fusion reaction ${}_1{}^2\mathrm{H}+{}_1{}^3\mathrm{H}\to {}_2{}^4\mathrm{He}+\mathrm{n}$ given that the repulsive potential energy between the two nuclei is $-7.7\times {10}^{-14} \mathrm{J}$, the temperature at which the gases must be heated to initiate the reaction is nearly
[Boltzmann’s constant $\mathrm{k}=1.38\times {10}^{-23} \mathrm{J}/\mathrm{K}$)
(a)${10}^9 \mathrm{K}$            (b) ${10}^7 \mathrm{K}$
(c) ${10}^5 \mathrm{K}$           (d)  ${10}^3 \mathrm{K}$

A nucleus with mass number 220 initially at rest emits an $\mathrm{\alpha }$-particle. If the Q value of the reaction is 5.5 MeV, calculate the kinetic energy of the $\mathrm{\alpha }$-particle

(1) 4.4 MeV             

(2) 5.4 MeV

(3) 5.6 MeV             

(4) 6.5 MeV

The half life of radioactive Radon is 3.8 days. The time at the end of which 1/20 th of the Radon sample will remain undecayed is
(Given ${\log }_{10}\mathrm{e}=0.4343$) 
(a) 3.8 days               (b) 16.5 days
(c) 33 days                (d) 76 days

If 10% of a radioactive material decays in 5 days, then the amount of original material left after 20 days is approximately
(1) 60%             

(2) 65%

(3) 70%             

(4) 75%

A radioactive isotope X with a half-life of $1.37\times {10}^9$ years decays to Y which is stable. A sample of rock from the moon was found to contain both the elements X and Y which were in the ratio of 1 : 7. The age of the rock is
(a) $1.96\times {10}^8$ years         (b) $3.85\times {10}^9$ years
(c) $4.11\times {10}^9$years          (d) $9.59\times {10}^9$ years

From a newly formed radioactive substance (Half-life 2 hours), the intensity of radiation is 64 times the permissible safe level. The minimum time after which work can be done safely from this source is:
1. 6 hours           
2. 12 hours
3. 24 hours         
4. 128 hours