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Assertion & Reason Test: Nuclei - Grade 12 MCQ


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10 Questions MCQ Test - Assertion & Reason Test: Nuclei

Assertion & Reason Test: Nuclei for Grade 12 2024 is part of Grade 12 preparation. The Assertion & Reason Test: Nuclei questions and answers have been prepared according to the Grade 12 exam syllabus.The Assertion & Reason Test: Nuclei MCQs are made for Grade 12 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Assertion & Reason Test: Nuclei below.
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Assertion & Reason Test: Nuclei - Question 1

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): Nuclear force is same between neutron-neutron, proton-proton and neutron proton.

Reason (R): Nuclear force is charge independent.

Detailed Solution for Assertion & Reason Test: Nuclei - Question 1
Nuclear force acts between nucleons. It is a powerful attractive force and acts in a very short distance. Neutrons are electrically neutral. So, neutronneutron is neither attractive nor repulsive force acting. So, Nuclear force binds them together. Protons are having +e charge each. They experience a repulsive force. But for the short distance, the attractive nuclear force is strong enough to overcome this force.

So, assertion and reason both are true and the reason explains the assertion.

Assertion & Reason Test: Nuclei - Question 2

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): The binding energy per nucleon, for nuclei with mass number (A) > 56 decreases with A.

Reason (R): Nuclear force is weak in heavier nuclei.

Detailed Solution for Assertion & Reason Test: Nuclei - Question 2
From the binding energy per nucleon vs. mass number, we find that binding energy per nucleon is maximum at A=56. After that, binding energy per nucleon decreases as A increases. So, the assertion is true.

Nuclear force remains the same for all nuclei. Hence the reason is false.

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Assertion & Reason Test: Nuclei - Question 3

Assertion (A) : The isotopes are the atoms of the same element with different atomic masses. They require different positions in the periodic table.
Reason (R) : Variable number of neutrons in the nuclei of the atoms of same elements leads to the different atomic masses.

Detailed Solution for Assertion & Reason Test: Nuclei - Question 3

A is false but R is true
Explanation: The isotopes are indeed atoms of the same element with different atomic masses due to different numbers of neutrons. However, they do not require different positions in the periodic table. Isotopes of the same element share the same chemical properties and thus occupy the same position in the periodic table. The atomic number, which determines an element's place in the periodic table, remains the same for all isotopes of a given element.

Assertion & Reason Test: Nuclei - Question 4

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): Electrons do not experience strong nuclear force.

Reason (R): Strong nuclear force is charge independent.

Detailed Solution for Assertion & Reason Test: Nuclei - Question 4
Nuclear force is a powerful attractive force acts as long as the distance between particles is within 10–15 m. This force is charge independent. But as distance increases, the effect of nuclear force rapidly falls. Electrons are distributed far away. The distance is beyond the range of the nuclear force. Hence nuclear force has no effect on electrons.

So, the assertion and reason both are true. But the reason does not explain the assertion.

Assertion & Reason Test: Nuclei - Question 5

Directions : In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.

Assertion (A): Density of all the nuclei is same.

Reason (R): Radius of nucleus is directly proportional to the cube root of mass number.

Detailed Solution for Assertion & Reason Test: Nuclei - Question 5
Radius of nucleus= R = R0A1/3.

So, Volume of nucleus, V =

Considering mass of proton = mass of neutron = m

The mass of the nucleus = M = mA

So, density = M/V =

So, the mean density is independent of mass number.

So, assertion and reason both are true and the reason properly explains the assertion.

Assertion & Reason Test: Nuclei - Question 6

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : Density of all the nuclei is the same.

Reason : Radius of nucleus is directly proportional to the cube root of mass number.

Detailed Solution for Assertion & Reason Test: Nuclei - Question 6
Experimentally, it is found that the average radius of a nucleus is given by R = R0A1/3 where R0 ​= 1.1 × 10−15 m = 1.1 fm

and A = mass number

Assertion & Reason Test: Nuclei - Question 7

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : The mass number of a nucleus is always less than its atomic number.

Reason : Mass number of a nucleus may be equal to its atomic number.

Detailed Solution for Assertion & Reason Test: Nuclei - Question 7
In case of hydrogen atom mass number and atomic number are equal.
Assertion & Reason Test: Nuclei - Question 8

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : Radioactivity of 108 undecayed radioactive nuclei of half life of 50 days is equal to that of 1.2 × 108 number of undecayed nuclei of some other material with half life of 60 days.

Reason : Radioactivity is proportional to half-life.

Detailed Solution for Assertion & Reason Test: Nuclei - Question 8
Radioactivity =

0.693 × 2 × 106.

Radioactivity is proportional to 1/T1/2 , and not to T1/2

Assertion & Reason Test: Nuclei - Question 9

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : Radioactive nuclei emit β–1 particles.

Reason : Electrons exist inside the nucleus.

Detailed Solution for Assertion & Reason Test: Nuclei - Question 9
Electrons are not inside the nucleus.
Assertion & Reason Test: Nuclei - Question 10

Directions: These questions consist of two statements, each printed as Assertion and Reason. While answering these questions, you are required to choose any one of the following four responses.

Assertion : The heavier nuclei tend to have larger N/Z ratio because neutrons do not exert electric force.

Reason : Coulomb forces have longer range compared to the nuclear force.

Detailed Solution for Assertion & Reason Test: Nuclei - Question 10
This is because in heavy nuclei, the N/Z ratio becomes larger in order to maintain their stability and reduce instability caused due to the repulsion among the protons.The neutrons exert only attractive short-range nuclear forces on each other as well as on the neighbouring protons, whereas the protons exert attractive short-range nuclear forces on each other as well as the electrostatic repulsive force. Thus, the nuclei with high mass numbers, in order to be stable, have a large neutron to proton ratio (N/Z).
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