Nucleus - NEET Physics Chapterwise MCQs & PYQs

NEET Nucleus MCQs & PYQs

Practice NEET Nucleus Questions

Question 71:

easy

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A): Binding energy per nucleon for atoms having mass number between \(30\) to \(170\), almost remains same.

Reason (R): Nuclear force is a short range force and hence get saturated.

In the light of the above statements, choose the correct answer from the options given below.

The binding energy per nucleon is nearly constant in the range \(30 < A < 170\) due to the short-range nature and saturation property of nuclear forces. Thus, both Assertion and Reason are true and the Reason is the correct explanation.

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Question 72:

easy

The correct statement regarding nuclear force is

Nuclear forces are very short-range forces (acting within femtometers) and they are charge independent, meaning the force between proton-proton, neutron-neutron, and proton-neutron is approximately the same.

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Question 73:

moderate

Consider the following statements:

(a) Nuclear density is directly proportional to cube root of mass number.

(b) Binding energy per nucleon is maximum for elements having mass number \(A > 170\).

(c) When two deuterium nuclei fuse together to form a tritium nucleus we get a proton.

(d) Neutrons and protons are bound in a nucleus by the short range weak nuclear force.

The correct statement(s) is/are

Only statement (c) is correct: \(2\text{H} + 2\text{H} \rightarrow 3\text{H} + 1\text{p}\). Nuclear density is independent of mass number, and binding energy per nucleon peaks around Iron \((A=56)\).

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Question 74:

moderate

A nucleus of mass number 238 at rest emits an alpha particle with kinetic energy \(5.4\text{ MeV}\). The Q value of reaction is

The relation between Q-value and kinetic energy is \(Q = K_{\alpha} \left(1 + \frac{m_{\alpha}}{M_{\text{daughter}}}\right) = 5.4 \times \left(1 + \frac{4}{234}\right) \approx 5.49\text{ MeV}\).

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Question 75:

easy

If the nucleus $^{27}_{13}Al$ has nuclear radius of about 3.6 fm, then $^{125}_{52}Te$ would have its radius approximately as:

(2007)

Using the relation $R \propto A^{1/3}$, we get $R_{Te} = R_{Al} (A_{Te} / A_{Al})^{1/3}$. $R_{Te} = 3.6 \times (125 / 27)^{1/3} = 3.6 \times (5 / 3) = 6.0 fm$.

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Question 76:

easy

The radius of germanium (Ge) nuclide is measured to be twice the radius of $^{9}_{4}Be$. The number of nucleons in Ge are:

(2006)

Given $R_{Ge} = 2 R_{Be}$, we can write $R_0 A_{Ge}^{1/3} = 2 R_0 (9)^{1/3}$. Canceling $R_0$ and cubing both sides gives $A_{Ge} = 2^3 \times 9 = 8 \times 9 = 72$. The number of nucleons is 72.

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Question 77:

easy

The nuclei of which one of the following pairs of nuclei are isotones?

(2005)

Isotones are nuclei with the same number of neutrons ($N = A - Z$). For $_{34}Se^{74}$, $N = 74 - 34 = 40$. For $_{31}Ga^{71}$, $N = 71 - 31 = 40$. Since both have 40 neutrons, they are isotones.

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Question 78:

easy

A nucleus represented by the symbol $^{A}_{Z}X$ has:

(2004)

In standard nuclear notation $^{A}_{Z}X$, Z represents the atomic number (number of protons) and A represents the mass number (total number of protons and neutrons). Hence, the number of neutrons is $A - Z$.

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Question 79:

easy

The mass number of a nucleus is:

(2003)

Mass number A is the sum of protons and neutrons, while atomic number Z is just the number of protons. For hydrogen ($^1H$), there are no neutrons, so A = Z. For all other stable nuclei, A > Z. Thus, it is sometimes equal.

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Question 80:

easy

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

(2003)

The radius of an atom is of the order of $10^{-10} m$, and the radius of a nucleus is of the order of $10^{-15} m$. The ratio of their volumes is proportional to the cube of their radii ratio: $(10^{-10} / 10^{-15})^3 = (10^5)^3 = 10^{15}$.

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