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Annihilation (destruction) of 1 gm of matter could theoretically yield energy of the order of:
1. 1eV
2. ${10}^{13}\mathrm{eV}$
3. ${10}^3\mathrm{eV}$
4. ${10}^{32}\mathrm{eV}$

The number of $\mathrm{\alpha } \mathrm{and} \mathrm{\beta }$ emitted during the radioactive decay chain starting from ${}_{88}\mathrm{Ra}_{226}$ and ending at ${}_{82}\mathrm{Pb}_{206}$ is:
1. $3\mathrm{\alpha }, 6\mathrm{\beta }$
2. $4\mathrm{\alpha }, 5\mathrm{\beta }$
3. $5\mathrm{\alpha }, 4\mathrm{\beta }$
4. $6\mathrm{\alpha }, 6\mathrm{\beta }$

To obtain an isotope of a radioactive atom, the atoms must emit:
1. One $\mathrm{\alpha }-\mathrm{and} \mathrm{one} \mathrm{\beta }$-particle
2. one $\mathrm{\alpha } \mathrm{and} \mathrm{two} \mathrm{\beta } \mathrm{particles}$
3. $\mathrm{two} \mathrm{\alpha } \mathrm{and} \mathrm{two} \mathrm{\beta } \mathrm{particles}$
4. $\mathrm{one} \mathrm{\alpha } \mathrm{and} \mathrm{four} \mathrm{\beta } \mathrm{particles}$

The position of ${}_1{}^2\mathrm{D}, {}_2{}^4\mathrm{He} \mathrm{and} {}_3{}^7\mathrm{Li}$ are shown on the binding energy curve as shown in figure. The energy released in the fusion reaction ${}_1{}^2\mathrm{D}+{}_3{}^7\mathrm{Li} \to 2 {}_2{}^4\mathrm{He}+{}_0{}^1\mathrm{n}$ will be closet to:

1. 20 MeV
2. 16 MeV
3. 8 MeV
4. 4MeV

A nucleus at rest disintegrates into two nuclear fragments with velocities in the ratio 8:27. The ratio of their nuclear radii will be:
1. 3:2
2. 9:4
3. 27:8
4. 8:27

A nucleus with an excess of neutrons may decay radioactively with the emission of:
1. a proton
2. a neutron
3. a positron
4. an electron

Which one of the following statement about uranium is correct?
1. ${}_{235}\mathrm{U}$ is fissionable by thermal neutrons.
2. Fast neutrons trigger the fission process in ${}_{235}\mathrm{U}$.
3. ${}_{238}\mathrm{U}$ breaks up into fragments, when bombarded by slow neutrons.
4. ${}_{235}U$ is an unstable isotope and undergoes spontaneous fission.

Two nuclei initially at rest undergo $\mathrm{\alpha }$-decay. If Q value of the process is same in the two cases the kinetic energy of the emitted $\mathrm{\alpha }$-particle will be:
1. equal in two cases
2. more for the heavier nucleus
3. more for the lighter nucleus
4. data insufficient
 

Statement 1: Nuclear fusion reactions for nuclei of small atomic mass (A<20) can take place only at high temperatures.
Statement 2: Nuclear fusion reactions for nuclei of small atomic mass (A<20) are exothermic.
1. Statement-1 is true, statement-2 is true and statement - 2 is correct explanation for statement-1.
2. Statement-1 is true, statement-2 is true and statement-2 is NOT the correct explanation for statement-1.
3. Statement-1 is true, statement-2 is false.
4. Statement-1 is false, statement-2 is true.

When $\frac{7}{4}$ Be transforms into $\frac{7}{3}$Li, it does so by:
1. emitting an electron
2. emitting a neutron
3. emitting a positron
4. emitting a proton

A sample of radioactive material has mass m, decay constant $\mathrm{\lambda }$ and molecular weight M. Avogadro constant=N. The initial activity of the sample is:
1. $\mathrm{\lambda m}$
2. $\frac{\mathrm{\lambda m}}{\mathrm{M}}$
3. $\frac{\mathrm{\lambda mN}}{\mathrm{M}}$
4. ${\mathrm{mNe}}^{\mathrm{\lambda }}$

In a sample of radioactive material, what percentage of the initial number of active nuclei will decay during one mean life?
1. 37%
2. 50%
3. 63%
4. 69.3%

90% of the active nuclei present in a radioactive sample are found to remain undecayed after 1 day. The percentage of the undecayed nuclei left after two days will be:
1. 85%
2. 81%
3. 80%
4. 79%

A sample of radio-nuclide contains ${10}^{18}$ atoms. The half-line of the material is 2.0 days, then the activity of a sample is:
1. $3.5\times {10}^{12}$ Bq
2. $4\times {10}^{11}$ Bq
3. $8\times {10}^{12}$ Bq
4. $4\times {10}^{12}$ Bq

A radioactive source has a half-life of 20-days. During a period of 60 days fraction of the atoms that have decayed would be:
1. 100%
2. 87.5%
3. 64%
4. 50%

A sample contains 16 gm of radioactive material, the half-life of which is two days. After 32 days, the amount of sample is:
1. less than 1 milligram
2. 1/4 gm
3. 1/2 gm
4. 1 gm

There are three lumps of radioactive substance. Their activities are in the ratio of 1:2:3. What will be the ratio of their activities at any future time?
1. 1:2:3
2. 2:1:3
3. 3:2:1
4. 2:3:1

A sample starts with 1000 radioactive atoms. How many half-lives have elapsed when 750 atoms have decayed?
1. 0.25
2. 1.5
3. 2.0
4. 2.5