Which of the following nucleus is unstable ?

Options

A. `""_(5)^(10)B`
B. `""_(4)^(10)Be`
C. `""_(7)^(14)N`
D. `""_(8)^(16)O`

Answer

B

Explanation

For stability n/p ratio should be close to one (valid only for lighter nuclides)
In case of `""_(5)^(10)B, ("neutron number")/("proton number") = (10-5)/(5) = 1, "In case of" ""_(4)^(10)Be, ("neutron number")/("proton number") = (10-4)/(4) = 1`.
In case of `""_(7)^(14)N, ("neutron number")/("proton number") = (14-7)/(7) = 1`, In case of `""_(8)^(16)O, ("neutron number")/("proton number") = (16-8)/(8) = 1`