Nuclei

The half life of radium is about 1600 years. Of 100 g of radium existing now, 25 g will remain unchanged after

1. 4800 years
2. 6400 years
3. 2400 years
4. 3200 years

Solar energy is mainly caused due to

1. burning of hydrogen in the oxygen
2. fission of uranium present in the Sun
3. fusion of protons during synthesis of heavier elements
4. gravitational contraction

The volume occupied by an atom is greater than the volume of the nucleus by a factor of about

1. 101
2. 105
3. 1010
4. 1015

The mass of proton is 1.0073 u and that of neutron is 1.0087 u (u = atomic mass unit). The binding energy of 42He is (Given helium nucleus mass ≈ 4.0015 u.)

1. 0.0305 J
2. 0.0305 erg
3. 28.4 MeV
4. 0.061 u

A sample of radioactive element has a mass of 10 g at an instant t = 0. The approximate mass of this element in the sample after two mean lives is

1. 1.35 g
2. 2.50 g
3. 3.70 g
4. 6.30 g

The mass number of a nucleus is

1. always less than its atomic number
2. always more than its atomic number
3. sometimes equal to its atomic number
4. sometimes less than and sometimes more than its atomic number

A nuclear reaction given by ZXA Z+1YA + -1e0 + represents

1. -decay
2. -decay
3. fusion
4. fission

Which of the following are suitable for the fusion process?

1. light nuclei
2. heavy nuclei
3. elements lying in the middle of the periodic table
4. middle elements, which are lying on binding energy curve.

A deuteron is bombarded on 8O16 nucleus, then an -particle is emitted. The product nucleus is

1. 7N13
2. 5B10
3. 4Be9
4. 7N14

A sample of radioactive element containing 4 1016 active nuclei. Half-life of element is 10 days, then number of decayed nuclei after 30 days

1. 0.5 1016
2. 2 1016
3. 3.5 1016
4. 1 1016