Question: Q. 1. A radioactive nucleus ’
The mass number and atomic number of
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Solution:
Ans. (i)
Atomic Number : 72
[Alternatively : Give full credit if student considers
${ }{72}^{180} \mathrm{~A} \xrightarrow{\alpha}{ }{70}^{176} A_{1} \xrightarrow{\beta}{ }^{176} A_{2} \xrightarrow{\alpha}{ }{69}^{172} A{3} \xrightarrow{\gamma}{ }{69}^{172} A{4}$
Gives the values quoted above.
If the student takes
$$ { }{72}^{180} \mathrm{~A} \xrightarrow{\alpha}{ }^{176} A{1} \xrightarrow{\beta^{+}}{ }^{176} A_{2} \xrightarrow{\alpha}{ }^{172} 69 A_{3} \xrightarrow{\gamma}{ }^{172} A_{4} $$
This would give the answers :
(ii) Basic nuclear process for
For
[Note : Give full credit of this part, if student writes the processes as conversion of proton into neutron for
[CBSE Marking Scheme2017]
