Two radioactive substances A and B have decay constants 5λ and λ respectively. At t = 0, they have the same number of nuclei. The ratio of the number of nuclei of A to those of B will be 1e2 after a time interval:
1. 14λ
2. 4λ
3. 2λ
4. 12λ
The binding energy of deuteron is 2.2 MeV and that of 2He4 is 28 MeV. If two deuterons are fused to form one 2He4, then the energy released is:
1. 25.8 MeV
2. 23.6 MeV
3. 19.2 MeV
4. 30.2 MeV
In a radioactive material, the activity at time t1 is R1 and at a later time t2, it is R2. If the decay constant of the material is λ, then:
1. R1=R2eλ(t1+t2)
2. R1=R2e-λ(t1-t2)
3. R1=R2(t1-t2)
4. R1=R2
A nucleus ZXA has a mass represented by M(A,Z). If MP and Mn denote the mass of proton and neutron respectively and BE the binding energy, then:
1. BE=[M(A,Z)-ZMp-(A-Z)Mn]c2
2. BE=[ZMp+(A-Z)Mn-M(A, Z)]c2
3. BE=[ZMp+AMn-M-(A, Z)]c2
4. BE=M(A, Z)-ZMp-(A-Z)Mn
In the radioactive decay process, the negatively charged emitted β-particles are:
1. | the electrons present inside the nucleus |
2. | the electrons produced as a result of the decay of neutrons inside the nucleus |
3. | the electrons produced as a result of collisions between atoms |
4. | the electrons orbiting around the nucleus |
Two nuclei have their mass numbers in the ratio of 1:3. The ratio of their nuclear densities would be:
1. 1:3
2. 3:1
3. (3)1/3:1
4. 1:1
If M(A, Z), Mp, and Mn denote the masses of the nucleus AZX, proton, and neutron respectively in units of u (1 u=931.5 MeV/c2) and represent its binding energy (BE) in MeV. Then:
1. | M(A,Z)=ZMp+(A−Z)Mn−BEc2 |
2. | M(A,Z)=ZMp+(A−Z)Mn+BE |
3. | M(A,Z)=ZMp+(A−Z)Mn−BE |
4. | M(A,Z)=ZMp+(A−Z)Mn+BEc2 |
The decay constants of two radioactive materials X1 and X2 are 5λ and λ respectively. Initially, they have the same number of nuclei. The ratio of the number of nuclei of X1 to that of X2 will be 1/e after a time:
1. λ
2. 12λ
3. 14λ
4. eλ
The number of beta particles emitted by a radioactive substance is twice the number of alpha particles emitted by it. The resulting daughter is an:
1. | isobar of a parent. | 2. | isomer of a parent. |
3. | isotone of a parent. | 4. | isotope of a parent. |
1. | β,α,γ | 2. | γ,β,α |
3. | β,γ,α | 4. | α,β,γ |