Nuclear chemistry: nuclear reactions, fission and fusion, radio-analytical techniques and activation analysis.
| YEAR | JUN-2016 | DEC-2015 | JUN-2015 | DEC-2014 | JUN-2014 | DEC-2013 | JUN-2013 | DEC-2012 | JUN-2012 | DEC-2011 | JUN-2011 |
| No.of questions appeared | 2 | 2 | 1 | 1 | 3 | – | 1 | – | 2 | 1 | 2 |
1.The carbon-14 activity of an old wood sample is found to be 14.2 disintegrations min-1g-1. Calculate age of oldwood sample, if for a fresh wood sample carbon-14 activity is 15.3 disintegrations min-1g-1(t1/2 carbon-14 is5730 years), is:
(a) 5, 000 years
(b) 4, 000 years
(c) 877 years
(d) 617 years
2.In ‘carbon-dating’ application of radioisotopes, 14C emits
(a) β -particle
(b) α -particle
(c) γ -radiation
(d) Positron.
3.The geometric cross-section (in barn) of a nucleus A = 125, ro = 1.4 × 10-15 m approximately is
(a) 1.05
(b) 1.54
(c) 2.05
(d) 2.54
4.The particles postulated to always accompany the positron emission among
(A) neutrino, (B) anti-neutrino, (C) electron,are
(a) A, B and C
(b) A and B
(c) A and C
(d) B and C
5.The nuclides among the following, capable of undergoing fission by thermal neutrons, are(A) 233U (B) 235U (C) 239Pu (D) 232Th
(a) A, B and D
(b) A, C and D
(c) B, C and D
(d) A, B and C
6.For a low energy nuclear reaction, 24Mg (d,α)22Na, the correct statements from the following are
(A) Kinetic energy of d particle is not fully available for exciting 24Mg.
(B) Total number of protons and neutrons is conserved
(C) Q value of nuclear reaction is much higher in magnitude relative to heat of chemical reaction
(D) Threshold energy is ≤Q value.
(a) A, B and C
(b) A, B and D
(c) B, C and D
(d) A, C and D
