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Staements I: .zX^4 undergoes 2 alpha-dec...

Staements I: `._zX^4` undergoes `2 alpha`-decays, `2 beta`-decays (negative `beta`) and `2 gamma`-decays. As a result, the daughter product is `._z._-2X^(A-B)`.
Staements II: In `alpha`-decay, the mass number decreases by 4 unit and atomic number decreases by `2` unit. In `beta`-decay (negative `beta`), the mass number remains unchanged and atomic number increases by `1` unit. In `gamma`-decay, mass number and atomic number remain unchanged.

A

If both assertion and reason are true and reason is the correct explanation of assertion.

B

If both assertion and reason are true but reason is not the correct explanation of assertion.

C

If assertion is true but reason is false

D

If assertion is false but reason is true.

Text Solution

Verified by Experts

The correct Answer is:
A
(a) In `alpha-`particle, the mass number decreases by `4` and atomic number decreases by `2`. In `beta-`decay, the mass number does not change but atomic number increases by `1`. In `gamma`-decay, the atomic and mass number remain unchanged.
The reaction can be summarised as
`._Z X^A overset (2 alpha)rarr ._(Z-4) Y^(A - 8) overset (2 beta)rarr ._(Z -2) Y^(A-8) overset (2 gamma)rarr ._(Z-2) Y^(A-8)`.
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Staements I: ._zX^4 undergoes 2 alpha -decays, 2 beta -decays (negative beta ) and 2 gamma -decays. As a result, the daughter product is ._z-2X^(A-B) . Staements II: In beta -decay, the mass number decreases by 4 unit and atomic number decreases by 2 unit. In beta -decay (negative beta ), the mass number remains unchanged and atomic number increases by 1 unit. In gamma -decay, mass number and atomic number remain unchanged.

A nucleus undertgoes beta -decay. How does its (i) mass number (ii) atomic number change ?

A nucleus of atomic mass A and atomic number Z emits beta- particle. The atomic mass and atomic number of the resulting nucleus are

In which of the following decays the atomic number decreases?

Assertion : After emission of one alpha -particle and two beta -particles, atomic number remains unchanged. Reason : Mass number changes by four.

In both beta^(-1) and beta^(+) decay processes, the mass number of a nucleus remains same, whereas the atomic number Z increases by one in beta^(-) decay and decreases by one in beta^(+) decay. Explain by giving reason.

Knowledge Check

  • This section contains Assertion and Reason type questions. Each question has 4 choice (1), (2), (3) and (4), out of which only one is correct. Assertion (A) _ZX^A undergoes 2alpha -decays, 2beta -decays and 2gamma -decays and the daughter product is z-2gamma^(A-8) Reason (R ) In alpha -decay, the mass number decreases by 4 and atomic number decreases by 2. In beta -decay, the mass number remains unchanged but atomic number increases by 1 only.

    A
    Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion
    B
    Both Assertion and Reason are correct but Reason is not the correct explanation of Assertion
    C
    Assertion is correct but Reason is incorrect
    D
    Assertion is incorrect but Reason is correct

  • A nucleus of atomic mass A and atomic number Z emits beta- particle. The atomic mass and atomic number of the resulting nucleus are

    A
    `A,Z`
    B
    `A + 1, Z`
    C
    `A, Z + 1`
    D
    `A - 4, Z - 2`

  • Assertion : After emission of one alpha -particle and two beta -particles, atomic number remains unchanged. Reason : Mass number changes by four.

    A
    (a) If both Assertion and Reason are true and Reason is correct explanation of the Assertion.
    B
    (b) If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
    C
    (c) If Assertion is true, but the Reason is false.
    D
    (d) If Assertion is false but the Reason is true.