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Q. No.Let nuclear densities of \({}_{2}^{4}{\mathrm{He}}\) and \({}_{20}^{40}{\mathrm{Ca}}\) be \(\rho_1\) and \(\rho_2\) respectively. Then \({{\rho_{1}}\over{\rho_{2}}}\) is equal to:
1. \(1:10\)
2. \(10:1\)
3. \(1:1\)
4. \(1:2\)
Subtopic: Nucleus |
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For the given radioactive decay reaction:
\(^{298}_{94}X \rightarrow ^{294}_{92}Y + { ^{4}_{2}\alpha} + Q\text-\text {value}\),
where the binding energy per nucleon of \(X,Y \) and \(\alpha\) are denoted by \(a, b \) and \(c\) respectively.
The expression for the \(Q\)-value is:
1. \((294 b +4c - 298 a)\)
2. \((92 b +2c - 94 a)\)
3. \((294 b +4c + 298 a)\)
4. \((92 b +2c + 94 a)\)
\(^{298}_{94}X \rightarrow ^{294}_{92}Y + { ^{4}_{2}\alpha} + Q\text-\text {value}\),
where the binding energy per nucleon of \(X,Y \) and \(\alpha\) are denoted by \(a, b \) and \(c\) respectively.
The expression for the \(Q\)-value is:
1. \((294 b +4c - 298 a)\)
2. \((92 b +2c - 94 a)\)
3. \((294 b +4c + 298 a)\)
4. \((92 b +2c + 94 a)\)
Subtopic: Nuclear Binding Energy |
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Level 1: 80%+
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Given below are two statements:
| Assertion (A): | Binding energy per nucleon for nuclei (atomic number \(30\) to \(107\)) is independent of atomic number. |
| Reason (R): | Nuclear force is short-range force. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | Both (A) and (R) are False. |
Subtopic: Nuclear Binding Energy |
Level 4: Below 35%
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An atom of atomic mass \(242,\) having binding energy per nucleon \(8.4\) MeV, breaks into two atoms of atomic mass \(121\) (each with binding energy per nucleon of \(7.1\) MeV). What would be the absolute \(Q\)-value of the reaction?
| 1. | \(150\) MeV | 2. | \(314.6\) MeV |
| 3. | \(208.4\) MeV | 4. | \(290.8\) MeV |
Subtopic: Nuclear Binding Energy |
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A has half life of 5 years. Find the amount of A left after 15 years.
1. \({{1}\over{8}}\) of initial value
2. \({{7}\over{8}}\) of initial value
3. \({{1}\over{4}}\) of initial value
4. \({{3}\over{4}}\) of initial value
1. \({{1}\over{8}}\) of initial value
2. \({{7}\over{8}}\) of initial value
3. \({{1}\over{4}}\) of initial value
4. \({{3}\over{4}}\) of initial value
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A radioactive nuclei X decays simultaneously to two nuclei \(Y\) and \(Z\) as:
\(t_{1 / 2}\) is 12 minutes while \(t'_{1/ 2}\) is 3 minutes. Find the time in which nuclei \(X\) decays 50%
1. 4.8 minutes
2. 15 minutes
3. 2.4 minutes
4. 9 minutes
\(t_{1 / 2}\) is 12 minutes while \(t'_{1/ 2}\) is 3 minutes. Find the time in which nuclei \(X\) decays 50%
1. 4.8 minutes
2. 15 minutes
3. 2.4 minutes
4. 9 minutes
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Decay constant for a radioactive nuclide is given to be \(2 \times 10^3\). If molar mass of sample is 60 gm then activity of 0.3 µgm sample is equal to (in disintegration/seconds)
1. \(6.023 \times 10^{15}\)
2. \(6.023 \times 10^{18}\)
3. \(6.023 \times 10^{12}\)
4. \(3.012 \times 10^{12}\)
1. \(6.023 \times 10^{15}\)
2. \(6.023 \times 10^{18}\)
3. \(6.023 \times 10^{12}\)
4. \(3.012 \times 10^{12}\)
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If half-life for a radio-active decay reaction is \(T\). Find the time after which \({7 \over 8}th\) of initial mass decays
1. \(3~T\)
2. \(2~T\)
3. \({T \over 2}\)
4. \(4 ~T\)
1. \(3~T\)
2. \(2~T\)
3. \({T \over 2}\)
4. \(4 ~T\)
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If a nucleus is divided in the ratio of \(1:2^{1/3},\) what is the ratio of the velocities of the resulting parts?
| 1. | \(2\) | 2. | \(2^{1/3}\) |
| 3. | \(2^{2/3}\) | 4. | \(2^{(-1/3)}\) |
Subtopic: Nucleus |
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If half life of a radioactive nuclide \(A\) is equal to average life of another radioactive nuclide \(B\). Find the ratio of decay constant of \(A\) to that of \(B\).
1. \(ln2 : 1\)
2. \(1 : ln2 \)
3. \(2 : ln2 \)
4. \(ln2 : 2\)
1. \(ln2 : 1\)
2. \(1 : ln2 \)
3. \(2 : ln2 \)
4. \(ln2 : 2\)
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