Previous year questions with solutions · 2000 – 2026
| Year | Questions | Papers | Avg / paper | Weightage |
|---|---|---|---|---|
| 2026 | 3 | 2 | 1.5 | 3.33% ▲ 11.1% vs last year |
| 2024 | 3 | 2 | 1.5 | 3.00% ▲ 50% vs last year |
| 2023 | 1 | 1 | 1 | 2.00% ▼ 50% vs last year |
| 2022 | 4 | 2 | 2 | 4.00% ▼ 33.3% vs last year |
| 2021 | 3 | 1 | 3 | 6.00% ▲ 35% vs last year |
| 2020 | 2 | 1 | 2 | 4.44% ▲ 100% vs last year |
| 2018 | 1 | 1 | 1 | 2.22% same as last year |
| 2017 | 1 | 1 | 1 | 2.22% ▲ 100% vs last year |
| 2016 | 1 | 2 | 0.5 | 1.11% ▼ 50% vs last year |
| 2015 | 2 | 2 | 1 | 2.22% ▼ 50% vs last year |
| 2014 | 2 | 1 | 2 | 4.44% same as last year |
| 2013 | 4 | 2 | 2 | 4.44% ▲ 18.5% vs last year |
| 2012 | 3 | 2 | 1.5 | 3.75% ▼ 40.8% vs last year |
| 2011 | 5 | 2 | 2.5 | 6.33% ▲ 28.2% vs last year |
| 2010 | 4 | 2 | 2 | 4.94% ▲ 21% vs last year |
| 2009 | 2 | 1 | 2 | 4.08% ▼ 36.1% vs last year |
| 2008 | 3 | 1 | 3 | 6.38% ▼ 25% vs last year |
| 2007 | 4 | 1 | 4 | 8.51% ▲ 41.8% vs last year |
| 2006 | 3 | 1 | 3 | 6.00% ▼ 29.5% vs last year |
| 2005 | 4 | 1 | 4 | 8.51% ▼ 2.1% vs last year |
| 2004 | 4 | 1 | 4 | 8.70% ▼ 24.6% vs last year |
| 2003 | 6 | 1 | 6 | 11.54% ▲ 80.8% vs last year |
| 2002 | 3 | 1 | 3 | 6.38% ▼ 37.4% vs last year |
| 2001 | 5 | 1 | 5 | 10.20% ▲ 53.1% vs last year |
| 2000 | 3 | 1 | 3 | 6.67% |
⚠ 42 of these questions are out of the current syllabus (marked on the question).
Two radioactive nuclei P and Q, in a given sample decay into a stable nucleus R. At time t = 0, the number of P species is 4N0 and that of Q is N0. Half-life of P (for conversion to R) is 1 minute whereas that of Q is 2 minutes. Initially there are no nuclei 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
The power obtained in a reactor using 235U disintegration is 1000 kW. The mass decay of 235U per hour is
Fusion reaction takes place at high temperature because
The half life of a radioactive isotope X is 50 years. It decays to another element Y which is stable. The two elements X and Y were found to be in the ratio of 1 : 15 in a sample of a given rock. The age of the rock was estimated to be
A nucleus mnX emits one particle and two particles. The resulting nucleus is
The binding energy per nucleon in deuterium and helium nuclei are 1.1 MeV and 7.0 MeV, respectively. When two deuterium nuclei fuse to form a helium nucleus the energy released in the fusion is
The decay constant of a radioisotope is . If A1 and A2 are its activities at times t1 and t2 respectively, the number of nuclei which have decayed during the time (t1 - t2)
The mass of a 73Li nucleus is 0.042 u less than the sum of the masses of all its nucleons. The binding energy per nucleon of 73Li nucleus is nearly
The activity of a radioactive sample is measured as N0 counts per minute at t = 0 and N0/e counts per minute at t = 5 minutes. The time (in minutes) at which the activity reduces to half its value is
In the nuclear decay given below AZX AZ+1Y A-4Z-1 B* A-4Z-1B, the particles emitted in the sequence are
The number of beta particles emitted by a radioactive substance is twice the number of alpha particles emitted by it. The resulting daughter is an
If M(A, Z), Mp and Mn denote the masses of the nucleus AZX, proton and neutron respectively in units of u (1 u = 931.5 MeV/c2) and BE represents its binding energy in MeV, then
Two nuclei have their mass numbers in the ratio of 1 : 3. The ratio of their nuclear densities would be
Two radioactive materials X1 and X2 have decay constants 5 and respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of X1 to that of X2 will be 1e after a time
A nucleus AZX has mass represented by M(A, Z). If Mp and Mn denote the mass of proton and neutron respectively and B.E. the binding energy in MeV, then
Two radioactive substances A and B have decay constants 5 and respectively. At t = 0 they have the same number of nuclei. The ratio of number of nuclei of A to those of B will be ( 1e )2 after a time interval
In a radioactive decay process, the negatively charged emitted -particles are
If the nucleus 2713Al has a nuclear radius of about 3.6 fm, then 12552Te would have its radius approximately as
The binding energy of deuteron is 2.2 MeV and that of 42He is 28 MeV. If two deuterons are fused to form one 42He then the energy released is
In a radioactive material the activity at time t1 is R1 and at a later time t2, it is R2. If the decay constant of the material is , then
The radius of germanium (Ge) nuclide is measured to be twice the radius of 94Be. The number of nucleons in Ge are
In the reaction 21H + 31H 42He + 10n, if the binding energies of 21H, 31H and 42He are respectively a, b and c (in MeV), then the energy (in MeV) released in this reaction is
In any fission process the ratio mass of fission productsmass of parent nucleus is
Fission of nuclei is possible because the binding energy per nucleon in them
Which one of the following pairs of nuclei are isotones ?
If M(A, Z), Mp and Mn denote the masses of the nucleus AZX, proton and neutron respectively in units of u (1 u = 931.5 MeV/c2) and BE represents its binding energy in MeV, then
If in a nuclear fusion process the masses of the fusing nuclei be m1 and m2 and the mass of the resultant nucleus be m3, then
A nucleus represented by the symbol AZX has
The half life of radium is about 1600 years. Of 100 g of radium existing now, 25 g will remain unchanged after
Solar energy is mainly caused due to