A positron is emitted from ${}_{11}^{23}\mathrm{Na}$. The ratio of the atomic mass and atomic number of the resulting nuclide is

JEE Advanced · 2007 · 08 Apr 2007 · Paper 2 · Chemical Kinetics

A positron is emitted from

_{11}^{23} Na

. The ratio of the atomic mass and atomic number of the resulting nuclide is

(A)22/10
(B)22/11
(C)23/10✓ Correct
(D)23/12

Answer: (C)

Solution

Positron emission is a type of beta-plus decay where a proton in the nucleus converts to a neutron:

p \to n + e^{+} + ν_{e}

. This decreases the atomic number by 1 but leaves the mass number unchanged. Starting with

_{11}^{23} Na

, after positron emission we get

_{10}^{23} Ne

. The ratio of atomic mass to atomic number is

\frac{23}{10}

JEE Advanced · 2007 · 08 Apr 2007 · Paper 2 · Single correct option

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