**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 ^{-1}g^{-1}. Calculate age of oldwood sample, if for a fresh wood sample carbon-14 activity is 15.3 disintegrations min^{-1}g^{-1}(t_{1/2} 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, ^{14}C emits**

** **(a) β -particle

(b) α -particle

(c) γ -radiation

(d) Positron.

**3.The geometric cross-section (in barn) of a nucleus A = 125, r****o ****= 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) ^{233}U (B) ^{235}U (C) ^{239}Pu (D) ^{232}Th**

(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, ^{24}Mg (d,α)^{22}Na, the correct statements from the following are**

(A) Kinetic energy of d particle is not fully available for exciting ^{24}Mg.

(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

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