# The radius of a nucleus of a mass number A is directly proportional to [MH CET 1999; AMU (En.) 2001; UPSEAT 2004; DUMET 2010] 1. ${A}^{3}$  2. A  3. ${A}^{2/3}$ 4. ${A}^{1/3}$

Subtopic:  Nuclear Binding Energy |
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${m}_{P}$ and ${m}_{n}$ are masses of proton and neutron respectively. An element of mass m has Z protons and N neutrons, then

1. $m>Z{m}_{p}+N{m}_{n}$

2. $m=Z{m}_{p}+N{m}_{n}$

3. $m

4. m may be greater than, less than or equal to $Z{m}_{p}+N{m}_{n}$, depending on the nature of the element.

Subtopic:  Mass-Energy Equivalent |
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The nuclei  can be described as [1990]

1. isotones

2. isobars

3. isotopes of carbon

4. isotopes of nitrogen

Subtopic:  Mass-Energy Equivalent |
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The radioactivity of a sample is ${A}_{1}$ at a time ${t}_{1}$ and ${A}_{2}$ at time ${t}_{2}$.  If the mean life of the specimen is T, the number of atoms that have disintegrated in the time interval of ${t}_{2}-{t}_{1}$ is:

1. ${A}_{1}-{A}_{2}$

2. $\frac{{A}_{1}-{A}_{2}}{T}$

3. $\left({A}_{1}-{A}_{2}\right)T$

4. ${A}_{1}{t}_{1}-{A}_{2}{t}_{2}$

Subtopic:  Radioactivity (OLD NCERT) |
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What is the radius of iodine atom? (atomic no. 53, mass no. 126) [1988]

1.

2.

3.

4.

Subtopic:  Nuclear Binding Energy |
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Which of the following statements is true for nuclear forces? [1990]

1. They obey the inverse square law of distance.

2. They obey the inverse third power law of distance.

3. They are short range forces.

4. They are equal in strength to electromagnetic forces.

Subtopic:  Nuclear Binding Energy |
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The relationship between disintegration constant $\left[\lambda \right]$ and half-life [T] will be:

1.

2.

3.

4.

Subtopic:  Radioactivity (OLD NCERT) |
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Alpha particles are

1. 2 free protons

2. helium atoms

3. singly ionized helium atoms

4. doubly ionised helium atoms

Subtopic:  Radioactivity (OLD NCERT) |
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A radioactive sample with a half-life of 1 month has the label: 'Activity = 2 microcurie on 1-8-1991'. What would be its activity two months earlier?

1. 1.0 microcurie

2. 0.5 microcurie

3. 4 microcurie

4. 8 microcurie

Subtopic:  Radioactivity (OLD NCERT) |
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If the nuclear force between two protons, two neutrons and between a proton and a neutron is denoted by $$F_{pp} ,F_{nn}$$ and $$F_{pn}$$ respectively, then:
1. $$F_{p p} \approx F_{n n} \approx F_{p n}$$
2. $$F_{p p} \neq F_{n n}$$ and $$F_{p n} = F_{n n}$$
3. $$F_{p p} = F_{n n} = F_{p n}$$
4. $$F_{p p} \neq F_{n n} \neq F_{p n}$$
Subtopic:  Nuclear Energy |
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