Atoms and Nuclei Test

Result

Atoms and Nuclei Test - 133

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Weekly Quiz Competition

Question 1
4 / -1

Half-life of a radioactive substance is 20 minutes. Difference between points of time when it is 33% disintegrated and 67% disintegrated is approximately

A
10 min

B
20 min

C
30 min

D
40 min

Solution
Question 2
4 / -1

Two radioactive materials X₁ and X₂have decay constants 10λ and λ respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of X₁ to that of X₂will be 1 /e after a time

A
1 /(10λ)

B
1 /(11λ )

C
11 /(10λ)

D
1 /(9λ )

Solution
Question 3
4 / -1

Half life of a radio-active substance is 20 minutes. The time between 20% and 80% decay will be

A
20 minutes

B
40 minutes

C
30 minutes

D
25 minutes

Solution
Question 4
4 / -1

Mass spectrometric analysis of potassium and argon atoms in a Moon rock sample shows that the ratio of the number of (stable) ⁴⁰Ar atoms present to the number of (radioactive) ⁴⁰K atoms is 10.3. Assume that all the argon atoms were produced by the decay of potassium atoms, with a half-life of 1.25 × 10⁹ yr. How old is the rock

A
2.95 × 10¹¹yr

B
2.95 × 10⁹yr

C
4.37 × 10⁹yr

D
4.37 × 10¹¹yr

Solution
Question 5
4 / -1

If one starts with one curie of radioactive substance(T_1/2 = 12 hrs) the activity left after a period of 1 week will be about

A
I curie

B
120 micro curie

C
60 micro curie

D
8 mili curie

Solution
Question 6
4 / -1

Two radioactive nuclei P and Q, in a given sample decay into a stable nucleus R. At time t = 0, number of P species are 4 N₀ and that of Q are N₀. Half-life of P (for conversion to R) is 1 minute where as that of Q is 2 minutes. Initially there are nonuclei of R present in the sample. When number of nuclei of P and Q are equal, the number of nuclei of R present in the sample would be

A

B

C

D

Solution
Question 7
4 / -1

An electron of a stationary hydrogen atom passes from the fifth energy level to the ground level. The velocity that the atom acquired as a result of photon emission will be

A
24 hR/25 m

B
25 hR/24 m

C
25 m/24 hR

D
24 m/25 hR

Solution
Question 8
4 / -1

The dependence of binding energy per nucleon, B_Nonthe mass number, A is represented by

A

B

C

D

Solution
Question 9
4 / -1

A

B

C

D

Solution
Question 10
4 / -1

A radioactive sample has N₀ active atoms at t = 0. If the rate of disintegration at any time is R and the number of atoms is N, then the ratio R /N varies with time as

A

B

C

D

Solution