Nuclear Chemistry Test

Result

Nuclear Chemistry Test - 11

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Weekly Quiz Competition

Question 1
4 / -1

A radioactive isotope has a half-life of 27 days. Starting with 4 g of the isotope, what will be mass remaining after 75 days ?

A
100 g

B
50 g

C
0.58 g

D
1.58 g

Solution
Question 2
4 / -1

A sample of rock from moon contains equal number of atoms of uranium and lead t_1/2 for U = 4.5 × 10⁹ yr. The age of the rock would be

A
2.25 × 10⁹ yr

B
13.5 × 10⁹ yr

C
9.0 × 10⁹ yr

D
4.5 × 10⁹ yr

Solution
Question 3
4 / -1

The half-life period of a radioactive material is 15 min. What percent of radioactivity of the material will remain after 45 min ?

A
17.5%

B
15%

C
12.5%

D
10%

Solution
Question 4
4 / -1

₈₄ Rn ²¹⁹ is a member of actinium series. The other member of this series is

A
₈₄ Ac ²²⁵

B
₉₀ Th ²³²

C
₁₅ P ³⁵

D
₉₂ U ²³⁵

Solution
Question 5
4 / -1

What is the half-life of ₆C¹⁴, if its disintegration constant is 2.31 × 10^-4 yr ^-1 ?

A
0.3 × 10⁴ yr

B
0.3 × 10³ yr

C
0.3 × 10⁸ yr

D
0.3 × 10² yr

Solution
Question 6
4 / -1

The activity of a radioactive substance falls to 87.5% of the initial value in 5 yr. What is the half-life of the element ?

A
52 yr

B
104 yr

C
26 yr

D
13 yr

Solution
Question 7
4 / -1

A radioactive isotope decays at such a rate that after 192 min only 1/16 of the original amount remains left. Its half-life is

A
32 min

B
48 min

C
12 min

D
24 min

Solution
Question 8
4 / -1

The activity of a radioactive nuclide is 2 × 10⁷ disintegrations per minute (dpm). After 23.03 min, its activity is reduced to 2 × 10⁶ dpm. What is the average life (in min) of this nuclide ?

A
100

B
10

C
1

D
0.1

Solution
Question 9
4 / -1

If the half-life of an isotope X is 10 yr, its decay constant is

A
6.932 yr ^-1

B
0.6932 yr ^-1

C
0.06932 yr ^-1

D
0.006932 yr ^-1

Solution
Question 10
4 / -1

A radioactive isotope has a half-life of 10 days. If today 125 mg is left over, what was its original weight 40 days earlier ?

A
2 g

B
600 mg

C
1 g

D
1.5 g

Solution