1)

A nuclear transformation  is given by   $Y(n,\alpha)\rightarrow _{3}Li^{7}$.The nucleus of elements Y is 


A) $ _{5}Be^{11}$

B) $ _{5}Be^{10}$

C) $ _{5}Be^{9}$

D) $ _{6}Cl^{12}$

Answer:

Option B

Explanation:

Y(n, $\alpha$)  the nucleus splits in to $\alpha$- particle and neutrons

 i.e,  $_{Z}Y^{A}+_{0}n^{1}\rightarrow_{3}Li^{7}+_{2}He^{4}$

 and Z+0=3 +2 or Z=5

 So, A+1=7+4

A=10
Hence , the nucleus of element Y is boron 

 $_{5}Y^{10}=_{5}B^{10}$