Nuclei Easy Questions and Answers | Page - 11

Nuclei

After 1α and 2 β-emissions

1. mass number reduces by 4
1. mass number reduces by 5
1. mass number reduces by 6
1. mass number increases by 4

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Emission of 1α particle led to decrease in atomic number by 2 while mass number by 4. On the other hand, emission of 2β particles increases atomic number by 2. Hence, overall emission of, 1α and 2β particles led to decrease in mass number by 4.

Correct Option: A

Emission of 1α particle led to decrease in atomic number by 2 while mass number by 4. On the other hand, emission of 2β particles increases atomic number by 2. Hence, overall emission of, 1α and 2β particles led to decrease in mass number by 4.

In a given reaction
_ZX^A → _{Z + 1}Y^A → _{Z - 1}K^{A - 4} → _{Z - 1}K^{A - 4}
Radioactive radiations are emitted in the sequence of

1. α, β, γ
1. γ, α, β
1. β, α, γ
1. γ, β, α

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Increase of charge number by 1 indicates β emission. Decrease of mass number by 4 and charge number by 2 indicates α emission. No change of mass number and charge number indicates γ-emission.

Correct Option: C

Increase of charge number by 1 indicates β emission. Decrease of mass number by 4 and charge number by 2 indicates α emission. No change of mass number and charge number indicates γ-emission.

The mass of α-particle is

1. less than the sum of masses of two protons and two neutrons
1. equal to mass of four protons
1. equal to mass of four neutrons
1. equal to sum of masses of two protons and two neutron

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α-particle = ₂He⁴, It contains 2 p and 2 n. As some mass is converted into B.E., therefore, mass of α particle is slightly less than the sum of the masses of 2 p and 2 n.

Correct Option: A

α-particle = ₂He⁴, It contains 2 p and 2 n. As some mass is converted into B.E., therefore, mass of α particle is slightly less than the sum of the masses of 2 p and 2 n.

An element A decays into element C by a two step process
A → B + ₂He⁴
B → C + 2e^-
Then

1. A and C are isotopes
1. A and C are isobars
1. A and B are isotopes
1. A and B are isobars

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From eqn. (ii), B has 2 units of charge more than C.
From eqn. (i), A loses 2 units of charge by emission of alpha particle. Hence, A and C are isotopes as their charge numbers are same.

Correct Option: A

From eqn. (ii), B has 2 units of charge more than C.
From eqn. (i), A loses 2 units of charge by emission of alpha particle. Hence, A and C are isotopes as their charge numbers are same.

Curie is a unit of

1. energy of gamma-rays
1. half-life
1. radioactivity
1. intensity of gamma-rays

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Curie is a unit of radioactivity.

Correct Option: C

Curie is a unit of radioactivity.