Binding energies $_{1} H^{2},_{2} H^{4},_{26} F e^{56}, a n d_{92} U^{235}$ of nuclei are 2.22MeV, 28.4MeV, 492MeV and 1768 MeV respectively. Which one of the following is more stable?

Q. In a radioactive sample

_{19}^{40} K

nuclei either decay into stable

_{20}^{40} C a

nuclei with decay constant

4.5 \times 10^{- 10}

per year or into stable

_{18}^{40} A r

nuclei with decay constant

0.5 \times 10^{- 10}

per year. Given that in this sample all the stable

_{20}^{40} C a

and

_{18}^{40} A r

nuclei are produced by the

_{19}^{40} K

nuclei only. In time

t \times 10^{9}

years, if the ratio of the sum of stable

_{20}^{40} C a

and

_{18}^{40} A r

nuclei to the radioactive

_{19}^{40} K

nuclei is

99

, the value of t will be? [Given: In

10 = 2.303

]

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Which of the following nuclei shown in the graph is light and stable?

The correct option is A D For light stable nuclides, the neutron number (N) is equal to the proton number (Z), so that the ratio NZ is equal to 1. Therefore, nucleus D is stable. Hence, option (D) is the correct answer.

The correct option is A $D$

For light stable nuclides, the neutron number $(N)$ is equal to the proton number $(Z)$ , so that the ratio $\frac{N}{Z}$ is equal to $1$ .

Therefore, nucleus $D$ is stable.

Hence, option $(D)$ is the correct answer.