JEE Questions for Chemistry Nuclear Chemistry Quiz 2 - MCQExams.com

If 8.0 g of a radioactive isotope has a half-life of 10 h. The half-life of 2.0 g of the same substance is
  • 2.5 h
  • 5 h
  • 10 h
  • 40 h
For a radioactive decay the value of K = 2.7 × 10-3 s-1 and initial concentration is 160 mol/L. After 100 s the concentration of radioactive element is
  • 72 mol/L
  • 122 mol/L
  • 50 mol/L
  • 80 mol/L
Half-life period of a radioactive element is 100 yr. How long will it take for its 93.75% decay ?
  • 400 yr
  • 300 yr
  • 200 yr
  • 193 yr
4n + 1 series is known by which name ?
  • Actinium
  • Neptunium
  • Thorium
  • Uranium
A freshly cut tree and a wooden artifact have 30.4 and 15.2 counts g-1 min-1 of C-14 of half-life of 5700 yr. The age of the artifact in years would be
  • 2850
  • 5700
  • 570
  • 6930
The half-life period of a radioactive isotope is 4.8 min. Starting with 1 mg of the isotope, how much of it would remain after 10 min ?
  • 0.5 mg
  • 0.726 mg
  • 0.126 mg
  • 0.236 mg
If 50% of a radioactive substance dissociates in 15 min, then the time taken by substance to dissociate 99% will be
  • 50 min
  • 100 min
  • 99 min
  • 150 min
A radioactive element gets spilled over the floor of a room. Its half-life period is 30 days. If the initial activity is ten times the permissible value, after how many days will it be safe to enter the room ?
  • 1000 days
  • 300 days
  • 10 days
  • 100 days
The half-life of a radioactive isotope is 3 h. If the initial mass of the isotope were 256 g, the mass of it remaining undecayed after 18 h would be
  • 4.0 g
  • 8.0 g
  • 12.0 g
  • 16.0 g
The radioactive isotope of cesium - 137 of weight 8 g was collected on 1st February, 2006 and kept in a sealed tube. On 1st July 2006 it was found that only 0.25 g of it remained. The half-life period of the isotope is
  • 37.5 days
  • 30 days
  • 25 days
  • 50 days
  • 60 days
The half-life period of radioactive element is 140 days. After 560 days, 1 g of element will reduce to

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    Chemistry-Nuclear Chemistry-5479.png

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Half-life of a radioactive element is 16 h. What time it will take for 75% disintegration ?
  • 32 days
  • 32 h
  • 48 h
  • 16 h
A sample of rock from moon contains equal number of atoms of uranium and lead t1/2 for U = 4.5 × 109 yr. The age of the rock would be
  • 2.25 × 109 yr
  • 13.5 × 109 yr
  • 9.0 × 109 yr
  • 4.5 × 109 yr
The half-life period of a radioactive material is 15 min. What percent of radioactivity of the material will remain after 45 min ?
  • 17.5%
  • 15%
  • 12.5%
  • 10%
84 Rn 219 is a member of actinium series. The other member of this series is
  • 84 Ac 225
  • 90 Th 232
  • 15 P 35
  • 92 U 235
What is the half-life of 6C14, if its disintegration constant is 2.31 × 10-4 yr -1 ?
  • 0.3 × 104 yr
  • 0.3 × 103 yr
  • 0.3 × 108 yr
  • 0.3 × 102 yr
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 ?
  • 52 yr
  • 104 yr
  • 26 yr
  • 13 yr
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
  • 32 min
  • 48 min
  • 12 min
  • 24 min
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 ?
  • 100
  • 10
  • 1
  • 0.1
If the half-life of an isotope X is 10 yr, its decay constant is
  • 6.932 yr -1
  • 0.6932 yr -1
  • 0.06932 yr -1
  • 0.006932 yr -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 ?
  • 2 g
  • 600 mg
  • 1 g
  • 1.5 g
T1/2 of C14 isotope is 5770 yr. Time after which 72% of isotope left is
  • 2740 yr
  • 274 yr
  • 2780 yr
  • 278 yr
A radioactive substance takes 20 min to decay 25%. How much time will be taken to decay 75% ?
  • 96.4 min
  • 68 min
  • 964 min
  • 680 min
The half-lives of two radioactive nuclides A and B are 1 and 2 min respectively. Equal weights of A and B are taken separately and allowed to disintegrate for 4 min. What will be the ratio of weights of A and B disintegrated ?
  • 1 : 1
  • 5 : 4
  • 1 : 2
  • 1 : 3
A wooden box excavated from Indus valley had an activity of 1.18 × 1013 disintegration per minute per g of carbon. What is the approximate age of this civilisation ?
  • 4000 yr
  • 5700 yr
  • 8100 yr
  • 6000 yr
Half-life of a substance A following first order kinetics is 5 days. Starting with 100 g of A, amount left 15 days is
  • 25 g
  • 50 g
  • 12.5 g
  • 6.25 g

Chemistry-Nuclear Chemistry-5500.png
  • X - 4 - Y
  • X - Y - 5
  • X - Y - 3
  • X - Y - 6
Identify the nuclear reaction that differs from the rest.
  • Positron emission
  • K - capture
  • β-decay
  • α-decay
  • γ-decay
Which of the following nuclear reactions will generate an isotope ?
  • Neutron particle emission
  • Positron emission
  • α-particle emission
  • β-particle emission

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