The half-life of a radioactive material is 3h. If the initial amount is 300g, then after 18h, it will remain

1. 4.68 g 

2. 46.8 g

3. 9.375 g 

4. 93.75 g

Half-life of a radioactive substance is 20 min. Difference between points of time when it is 33% disintegrated and 67% disintegrated is approximately-

1. 10 min

2. 20 min 

3. 30 min

4. 40  min

When two deuterium nuclei fuse together to form a tritium nuclei, we get a

1. Neutron

2. Deutron

3. $\alpha$-particle

4. Proton

The most penetrating radiation out of the following is 

1. $\gamma$-rays 

2. $\alpha$-particles

3. $\beta$-rays 

4. X-rays

In any fission process the ratio $\frac{mass of fission products}{mass of parent nucleus}$ is         

1. less than 1

2. greater  than 1

3. equal to 1

4. depends on the mass of parent nucleus

The nucleus ${}_{48}C{d}^{115}$, after two successive $\beta$-decay will give

1. ${}_{46}P{a}^{115}$   

2. ${}_{49}I{n}^{114}$

3. ${}_{50}S{n}^{113}$   

4. ${}_{50}S{n}^{115}$

In nuclear fission process, energy is released because 

1. mass of products is more than mass of nucleus.

2. total binding energy of products formed due to nuclear fission is more than that the parent fissionable material.

3. total binding energy of products formed due to nuclear fission is less than parent fissionable material.

4. mass of some particles is converted into energy.

The average binding energy of a nucleon inside an atomic nucleus is about 

1. 8 MeV

2. 8 eV

3. 8 J 

4. 8 erg

A nucleus with Z = 92 emits the following in a sequence:

$\alpha , {\beta }^{-}, {\beta }^{-}, \alpha , \alpha , \alpha , \alpha , \alpha , {\beta }^{-},{\beta }^{-}, \alpha , {\beta }^{+}, {\beta }^{+}, \alpha$. The Z of the resulting nucleus is [AIEEE 2003]

1. 74 

2. 76 

3. 78

4. 82

In nuclear fission, the percentage of mass converted into energy is about

1.  1%

2.  0.1%

3.  0.01%

4.  10%