A radioactive nucleus 'A' undergoes a series of decays according to the following scheme: $A \xrightarrow{\;\alpha\;} A_1 \xrightarrow{\;\beta^{-}\;} A_2 \xrightarrow{\;\alpha\;} A_3 \xrightarrow{\;\gamma\;} A_4$. The mass number and atomic number of $A$ are 180 and 72 respectively. What are these numbers for $A_4$?

CBSE Class 12 · 2009 · Modern PhysicsShort Answer

A radioactive nucleus 'A' undergoes a series of decays according to the following scheme:

A α A_{1} β^{-} A_{2} α A_{3} γ A_{4}

. The mass number and atomic number of

A

are 180 and 72 respectively. What are these numbers for

A_{4}

Answer: $A_{4}$ : mass number $172$ , atomic number $69$ .

Track the changes step by step starting from

A (180, 72)

A (180, 72) α A_{1} (176, 70) β^{-} A_{2} (176, 71) α A_{3} (172, 69) γ A_{4} (172, 69) .

(

γ

emission changes neither

A

nor

Z

A_{4} : mass number 172, atomic number 69

CBSE Class 12 Board · 2009 · Subjective