1
JEE Main 2022 (Online) 28th July Evening Shift
+4
-1

A radioactive sample decays $$\frac{7}{8}$$ times its original quantity in 15 minutes. The half-life of the sample is

A
5 min
B
7.5 min
C
15 min
D
30 min
2
JEE Main 2022 (Online) 28th July Morning Shift
+4
-1

The equation $$\lambda=\frac{1.227}{x} \mathrm{~nm}$$ can be used to find the de-Brogli wavelength of an electron. In this equation $$x$$ stands for :

Where

$$\mathrm{m}=$$ mass of electron

$$\mathrm{P}=$$ momentum of electron

$$\mathrm{K}=$$ Kinetic energy of electron

$$\mathrm{V}=$$ Accelerating potential in volts for electron

A
$$\sqrt{\mathrm{mK}}$$
B
$$\sqrt{\mathrm{P}}$$
C
$$\sqrt{\mathrm{K}}$$
D
$$\sqrt{\mathrm{V}}$$
3
JEE Main 2022 (Online) 27th July Evening Shift
+4
-1

The activity of a radioactive material is $$6.4 \times 10^{-4}$$ curie. Its half life is 5 days. The activity will become $$5 \times 10^{-6}$$ curie after :

A
7 days
B
15 days
C
25 days
D
35 days
4
JEE Main 2022 (Online) 27th July Morning Shift
+4
-1

What is the half-life period of a radioactive material if its activity drops to $$1 / 16^{\text {th }}$$ of its initial value in 30 years?

A
9.5 years
B
8.5 years
C
7.5 years
D
10.5 years
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