MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 12583 Mcqs, each offering curated multiple-choice questions to sharpen your Joint Entrance Exam - Main (JEE Main) knowledge and support exam preparation. Choose a topic below to get started.
| 3601. |
A radioactive material has a half-life of 8 years. The activity of the material will decrease to about 1/8 of its original value in [UPSEAT 2005] |
| A. | 256 year |
| B. | 128 year |
| C. | 64 year |
| D. | 24 year |
| Answer» E. | |
| 3602. |
Starting with a sample of pure \[^{66}Cu,\,\frac{7}{8}\] of it decays into Zn in 15 min. The corresponding half-life is [AIEEE 2005] |
| A. | 5 min |
| B. | \[7\frac{1}{2}\] min |
| C. | 10 min |
| D. | 15 min |
| Answer» B. \[7\frac{1}{2}\] min | |
| 3603. |
A radioactive material has a half-life of 10 days. What fraction of the material would remain after 30 days [AIIMS 2005] |
| A. | 0.5 |
| B. | 0.25 |
| C. | 0.125 |
| D. | 0.33 |
| Answer» D. 0.33 | |
| 3604. |
The decay constant \[\lambda \] of the radioactive sample is the probability of decay of an atom in unit time, then [CBSE PMT 1990] |
| A. | \[\lambda \] decreases as atoms become older |
| B. | \[\lambda \] increases as the age of atoms increases |
| C. | \[\lambda \] is independent of the age |
| D. | Behaviour of \[\lambda \] with time depends on the nature of the activity |
| Answer» D. Behaviour of \[\lambda \] with time depends on the nature of the activity | |
| 3605. |
The half-life of a radioactive substance is 3.6 days. How much of 20 mg of this radioactive substance will remain after 36 days [Pb. PMT 2003] |
| A. | 0.0019 mg |
| B. | 1.019 mg |
| C. | 1.109 mg |
| D. | 0.019 mg |
| Answer» E. | |
| 3606. |
The half-life of a radioactive substance is 40 years. How long will it take to reduce to one fourth of its original amount and what is the value of decay constant [DPMT 2003] |
| A. | 40 year, 0.9173/year |
| B. | 90 year, 9.017/year |
| C. | 80 year, 0.0173 year |
| D. | None of these |
| Answer» D. None of these | |
| 3607. |
Activity of radioactive element decreased to one third of original activity \[{{R}_{0}}\] in 9 years. After further 9 years, its activity will be [DCE 2002] |
| A. | \[{{R}_{0}}\] |
| B. | \[\frac{2}{3}{{R}_{0}}\] |
| C. | \[{{R}_{0}}/9\] |
| D. | \[{{R}_{0}}/6\] |
| Answer» D. \[{{R}_{0}}/6\] | |
| 3608. |
The half-life of radium is about 1600 years. Of 100 g of radium existing now, 25 g will remain unchanged after [CBSE PMT 2004] |
| A. | 2400 years |
| B. | 3200 years |
| C. | 4800 years |
| D. | 6400 years |
| Answer» C. 4800 years | |
| 3609. |
A count rate meter shows a count of 240 per minute from a given radioactive source. One hour later the meter shows a count rate of 30 per minute. The half-life of the source is [KCET 2004] |
| A. | 120 min |
| B. | 80 min |
| C. | 30 min |
| D. | 20 min |
| Answer» E. | |
| 3610. |
Carbon dating is best suited for determining the age of fossils if their age in years is of the order of [AIIMS 2004] |
| A. | \[{{10}^{3}}\] |
| B. | \[{{10}^{4}}\] |
| C. | \[{{10}^{5}}\] |
| D. | \[{{10}^{6}}\] |
| Answer» C. \[{{10}^{5}}\] | |
| 3611. |
The half-life of a sample of a radioactive substance is 1 hour. If \[8\times {{10}^{10}}\] atoms are present at \[t=0\], then the number of atoms decayed in the duration \[t=2\] hour to \[t=4\] hour will be [MP PMT 2004] |
| A. | \[2\times {{10}^{10}}\] |
| B. | \[1.5\times {{10}^{10}}\] |
| C. | Zero |
| D. | Infinity |
| Answer» C. Zero | |
| 3612. |
A radioactive decay chain starts from \[_{93}N{{p}^{237}}\] and produces \[_{90}T{{h}^{229}}\] by successive emissions. The emitted particles can be [MP PMT 2004] |
| A. | Two a-particles and one b-particle |
| B. | Three \[{{\beta }^{+}}\] particles |
| C. | One a particle and two \[{{\beta }^{+}}\] particles |
| D. | One a particle and two \[{{\beta }^{-}}\] particles |
| Answer» B. Three \[{{\beta }^{+}}\] particles | |
| 3613. |
Radioactive nuclei that are injected into a patient collect at certain sites within its body, undergoing radioactive decay and emitting electromagnetic radiation. These radiations can then be recorded by a detector. This procedure provides an important diagnostic tool called [AIIMS 2003] |
| A. | Gamma camera |
| B. | CAT scan |
| C. | Radiotracer technique |
| D. | Gamma ray spectroscopy |
| Answer» D. Gamma ray spectroscopy | |
| 3614. |
A nucleus with Z = 92 emits the following in a sequence: \[\alpha ,\,{{\beta }^{-}},\,{{\beta }^{-}},\,\alpha ,\alpha ,\alpha ,\alpha ,\alpha ,{{\beta }^{-}},\,{{\beta }^{-}},\alpha ,\,{{\beta }^{+}},\,{{\beta }^{+}},\,\alpha \]. The Z of the resulting nucleus is [AIEEE 2003] |
| A. | 74 |
| B. | 76 |
| C. | 78 |
| D. | 82 |
| Answer» D. 82 | |
| 3615. |
Radioactivity was discovered by |
| A. | Becquerel |
| B. | Pierre Curie |
| C. | Roentgen |
| D. | Rutherford |
| Answer» B. Pierre Curie | |
| 3616. |
A radioactive sample at any instant has its disintegration rate 5000 disintegration per minute. After 5 minutes, the rate is 1250 disintegrations per minute. Then, the decay constant (per minute) is [AIEEE 2003] |
| A. | 0.8 In 2 |
| B. | 0.4 In 2 |
| C. | 0.2 In 2 |
| D. | 0.1 In 2 |
| Answer» C. 0.2 In 2 | |
| 3617. |
A sample of radioactive element has a mass of 10 gm at an instant t = 0.The approximate mass of this element in the sample after two mean lives is [CBSE PMT 2003] |
| A. | 2.50 gm |
| B. | 3.70 gm |
| C. | 6.30 gm |
| D. | 1.35 gm |
| Answer» E. | |
| 3618. |
A radioactive substance has an average life of 5 hours. In a time of 5 hours [Orissa JEE 2003] |
| A. | Half of the active nuclei decay |
| B. | Less than half of the active nuclei decay |
| C. | More than half of the active nuclei decay |
| D. | All active nuclei decay |
| Answer» D. All active nuclei decay | |
| 3619. |
The half-life of a radioactive substance is 48 hours. How much time will it take to disintegrate to its \[\frac{1}{16}\]th part [BCECE 2003] |
| A. | 12 h |
| B. | 16 h |
| C. | 48 h |
| D. | 192 h |
| Answer» E. | |
| 3620. |
The half-life of \[^{215}At\] is \[100\mu s\]. The time taken for the radioactivity of a sample of \[^{215}At\] to decay to 1/16th of its initial value is [IIT-JEE (Screening) 2002] |
| A. | \[400\,\mu s\] |
| B. | \[6.3\,\mu s\] |
| C. | \[40\,\mu s\] |
| D. | \[300\mu s\] |
| Answer» B. \[6.3\,\mu s\] | |
| 3621. |
Which of the following processes represents a gamma-decay [IIT-JEE (Screening) 2002] |
| A. | \[^{A}{{X}_{Z}}+\gamma \,\to {{\,}^{A}}{{X}_{Z-1}}+a+b\] |
| B. | \[^{A}{{X}_{Z}}{{+}^{1}}{{n}_{0}}\,\to {{\,}^{A-3}}{{X}_{Z-2}}+c\] |
| C. | \[^{A}{{X}_{Z}}\,\to {{\,}^{A}}{{X}_{Z}}+f\] |
| D. | \[^{A}{{X}_{Z}}+{{e}_{-1}}\,\to {{\,}^{A}}{{X}_{Z-1}}+g\] |
| Answer» D. \[^{A}{{X}_{Z}}+{{e}_{-1}}\,\to {{\,}^{A}}{{X}_{Z-1}}+g\] | |
| 3622. |
Nucleus produced due to a-decay of the nucleus \[_{Z}{{X}^{A}}\] is [MP PET 2002] |
| A. | \[_{Z+2}{{Y}^{A+4}}\] |
| B. | \[_{Z}{{Y}^{A}}\] |
| C. | \[_{Z-2}{{Y}^{A-4}}\] |
| D. | \[_{Z-4}{{Y}^{A-2}}\] |
| Answer» D. \[_{Z-4}{{Y}^{A-2}}\] | |
| 3623. |
The radioactivity of a certain radioactive element drops to 1/64 of its initial value in 30 seconds. Its half-life is [CPMT 1990, 97] |
| A. | 2 seconds |
| B. | 4 seconds |
| C. | 5 seconds |
| D. | 6 seconds |
| Answer» D. 6 seconds | |
| 3624. |
The activity of a sample of a radioactive material is A, at time \[{{t}_{1}}\] and \[{{A}_{2}}\] at time \[{{t}_{2}}\] \[({{t}_{2}}>{{t}_{1}}).\] If its mean life T, then [BHU 2002] |
| A. | \[{{A}_{1}}{{t}_{1}}={{A}_{2}}{{t}_{2}}\] |
| B. | \[{{A}_{1}}-{{A}_{2}}={{t}_{2}}-{{t}_{1}}\] |
| C. | \[{{A}_{2}}={{A}_{1}}{{e}^{({{t}_{1}}-{{t}_{2}})/T}}\] |
| D. | \[{{A}_{2}}={{A}_{1}}{{e}^{({{t}_{1}}/{{t}_{2}})T}}\] |
| Answer» D. \[{{A}_{2}}={{A}_{1}}{{e}^{({{t}_{1}}/{{t}_{2}})T}}\] | |
| 3625. |
If \[_{92}{{U}^{238}}\] undergoes successively 8 a-decays and 6 b-decays, then resulting nucleus is [CBSE PMT 2002] |
| A. | \[_{82}{{U}^{206}}\] |
| B. | \[_{82}P{{b}^{206}}\] |
| C. | \[_{82}{{U}^{210}}\] |
| D. | \[_{82}{{U}^{214}}\] |
| Answer» C. \[_{82}{{U}^{210}}\] | |
| 3626. |
A radioactive substance emits [MP PET 2002] |
| A. | Electromagnetic radiation |
| B. | Electrons revolving around the nucleus |
| C. | Charged particles |
| D. | Neutral particles |
| Answer» D. Neutral particles | |
| 3627. |
The ratio activity of an element becomes 1/64th of its original value in 60 sec. Then the half life period is [MP PMT 2002] |
| A. | 5 sec |
| B. | 10 sec |
| C. | 20 sec |
| D. | 30 sec |
| Answer» C. 20 sec | |
| 3628. |
The equation \[_{z}{{X}^{A}}\,\to {{\,}_{z+1}}{{Y}^{A}}{{+}_{-1}}{{e}^{0}}+\bar{v}\] is [CPMT 2002] |
| A. | b-emission |
| B. | a-emission |
| C. | e? capture |
| D. | Fission |
| Answer» B. a-emission | |
| 3629. |
If \[{{N}_{0}}\] is the original mass of the substance of half life period \[{{T}_{1/2}}=5\] years, then the amount of substance left after 15 years is [AIEEE 2002] |
| A. | \[{{N}_{0}}/8\] |
| B. | \[{{N}_{0}}/16\] |
| C. | \[{{N}_{0}}/2\] |
| D. | \[{{N}_{0}}/4\] |
| Answer» B. \[{{N}_{0}}/16\] | |
| 3630. |
Half-life of a substance is 10 years. In what time, it becomes \[\frac{1}{4}\]th part of the initial amount [AIEEE 2002] |
| A. | 5 years |
| B. | 10 years |
| C. | 20 years |
| D. | None of these |
| Answer» D. None of these | |
| 3631. |
A radioactive material has an initial amount 16 gm. After 120 days it reduces to 1 gm, then the half-life of radioactive material is [CPMT 2003] |
| A. | 60 days |
| B. | 30 days |
| C. | 40 days |
| D. | 240 days |
| Answer» C. 40 days | |
| 3632. |
The S.I. unit of radioactivity is [KCET 2002] |
| A. | Roentgen |
| B. | Rutherford |
| C. | Curie |
| D. | Becqueral |
| Answer» E. | |
| 3633. |
In a sample of radioactive material, what percentage of the initial number of active nuclei will decay during one mean life [KCET 2002] |
| A. | 69.3% |
| B. | 63% |
| C. | 50% |
| D. | 37% |
| Answer» C. 50% | |
| 3634. |
The half-life of a radioactive substance against a-decay is \[1.2\times {{10}^{7}}s\]. What is the decay rate for \[4\times {{10}^{15}}\] atoms of the substance [AMU (Med.) 2002] |
| A. | \[4.6\times {{10}^{12}}atoms/s\] |
| B. | \[2.3\times {{10}^{11}}atoms/s\] |
| C. | \[4.6\times {{10}^{10}}atoms/s\] |
| D. | \[2.3\times {{10}^{8}}\] |
| Answer» E. | |
| 3635. |
The decay constant of a radioactive element is \[1.5\times {{10}^{-9}}\] per second. Its mean life in seconds will be [MP PET 2001] |
| A. | \[1.5\times {{10}^{9}}\] |
| B. | \[4.62\times {{10}^{8}}\] |
| C. | \[6.67\times {{10}^{8}}\] |
| D. | \[10.35\times {{10}^{8}}\] |
| Answer» D. \[10.35\times {{10}^{8}}\] | |
| 3636. |
In the disintegration series \[_{92}^{238}U\xrightarrow{\alpha }x\xrightarrow{\beta }_{Z}^{A}y\] The value of Z and A respectively will be [MP PET 2001; MP PMT 2001] |
| A. | 92, 236 |
| B. | 88, 230 |
| C. | 90, 234 |
| D. | 91, 234 |
| Answer» E. | |
| 3637. |
Certain radio-active substance reduces to 25% of its value in 16 days. Its half-life is [MP PMT 2001] |
| A. | 32 days |
| B. | 8 days |
| C. | 64 days |
| D. | 28 days |
| Answer» E. | |
| 3638. |
1 mg gold undergoes decay with 2.7 days half-life period, amount left after 8.1 days is [UPSEAT 2001] |
| A. | 0.91 mg |
| B. | 0.25 mg |
| C. | 0.5 mg |
| D. | 0.125 mg |
| Answer» E. | |
| 3639. |
99% of a radioactive element will decay between [AMU (Engg.) 2001] |
| A. | 6 and 7 half lives |
| B. | 7 and 8 half lives |
| C. | 8 and 9 half lives |
| D. | 9 half lives |
| Answer» B. 7 and 8 half lives | |
| 3640. |
A radioactive nucleus with Z protons and N neutrons emits an a-particle, 2b-particles and 2 gamma rays. The number of protons and neutrons in the nucleus left after the decay respectively, are [AMU (Engg.) 2001] |
| A. | Z ? 3, N ? 1 |
| B. | Z ? 2, N ? 2 |
| C. | Z ? 1, N ? 3 |
| D. | Z, N ? 4 |
| Answer» E. | |
| 3641. |
In which of the following decay, the element does not change [MH CET (Med.) 2001] |
| A. | b-decay |
| B. | a-decay |
| C. | g-decay |
| D. | None of these |
| Answer» D. None of these | |
| 3642. |
If a radioactive substance reduces to \[\frac{1}{16}\] of its original mass in 40 days, what is its half-life [DCE 2001; AIIMS 2003] |
| A. | 10 days |
| B. | 20 days |
| C. | 40 days |
| D. | None of these |
| Answer» B. 20 days | |
| 3643. |
Half-life of \[B{{i}^{210}}\] is 5 days. If we start with 50,000 atoms of this isotope, the number of atoms left over after 10 days is [MP PET 1993] |
| A. | 5,000 |
| B. | 25,000 |
| C. | 12,500 |
| D. | 20,000 |
| Answer» D. 20,000 | |
| 3644. |
A radioactive nucleus emits a beta particle. The parent and daughter nuclei are [EAMCET (Engg.) 2001] |
| A. | Isotopes |
| B. | Isotones |
| C. | Isomers |
| D. | Isobars |
| Answer» E. | |
| 3645. |
Half-life is measured by [RPET 2001] |
| A. | Geiger-Muller counter |
| B. | Carbon dating |
| C. | Spectroscopic method |
| D. | Wilson-Cloud chamber |
| Answer» B. Carbon dating | |
| 3646. |
During negative b-decay [RPET 2001] |
| A. | Neutron converts into proton |
| B. | Proton converts into neutron |
| C. | Neutron proton ratio increases |
| D. | None of these |
| Answer» B. Proton converts into neutron | |
| 3647. |
The electron emitted in beta radiation originates from [IIT JEE (Screening) 2001] |
| A. | Inner orbits of atoms |
| B. | Free electrons existing in nuclei |
| C. | Decay of a neutron in a nucleus |
| D. | Photon escaping from the nucleus |
| Answer» D. Photon escaping from the nucleus | |
| 3648. |
In the given nuclear reaction, how many a and b particles are emitted \[_{92}{{X}^{235}}\to {{\ }_{82}}{{Y}^{207}}\] [AFMC 2001] |
| A. | 3a particles and 2b particle |
| B. | 4a particles and 3b particle |
| C. | 6a particles and 4b particle |
| D. | 7a particles and 4b particle |
| Answer» E. | |
| 3649. |
1 Curie is equal to [BHU 2001] |
| A. | \[3\times {{10}^{10}}\] disintegrations/sec |
| B. | \[3.7\times {{10}^{7}}\] disintegrations/sec |
| C. | \[5\times {{10}^{7}}\] disintegrations/sec |
| D. | \[3.7\times {{10}^{10}}\] disintegrations/sec |
| Answer» E. | |
| 3650. |
During mean life of a radioactive element, the fraction that disintegrates is [CPMT 2001] |
| A. | e |
| B. | \[\frac{1}{e}\] |
| C. | \[\frac{e-1}{e}\] |
| D. | \[\frac{e}{e-1}\] |
| Answer» D. \[\frac{e}{e-1}\] | |