Nuclear (Physics) Part-I

Total Questions: 50

31. Hydrogen bomb is based on the principle of- [U.P.P.C.S (Pre) 2010, 67ᵗʰ B.P.S.C. (Pre) 2022]

Correct Answer: (b) Uncontrolled fusion reaction
Solution:

Hydrogen bomb's enormous explosive power results from an uncontrolled, self-sustaining chain reaction in which isotopes of hydrogen (deuterium and tritium) combined under extremely high temperature and pressure to form helium in a process known as nuclear fusion.

32. Hydrogen bomb was developed by: [U.P.P.C.S. (Mains) 2015]

Correct Answer: (a) Edward Teller
Solution:

Edward Teller, one of the most famous scientists of 20% century was known as "father of hydrogen bomb". He was born in January, 1908 in Hungary.

In November, 1952 the United States conducted its first nuclear test of a fusion bomb or 'hydrogen bomb' at Eniwetok in Marshall Island.

33. Enriched Uranium is- [U.P.P.C.S. (Pre) 2009, 67ᵗʰ B.P.S.C. (Pre) 2022]

Correct Answer: (b) Natural uranium in which radioactive U²³⁵ isotope is increased artificially.
Solution:

Enriched Uranium' is a type of uranium in which the proportion of the uranium-235 isotope has been increased from the natural level by the process of isotope separation.

34. The ultimate product of radioactive disintegration of uranium is- [Chhattisgarh P.C.S (Pre) 2013]

Correct Answer: (a) Lead
Solution:

Uranium is the first in a long chain of radioactive elements that decay until the stable element lead is formed.

35. A radioactive substance has a half-life of four months. Three-fourth of the substance would decay in- [I.A.S. (Pre) 2001]

Correct Answer: (c) 8 months
Solution:

36. The half-life of a radioactive element is 5 years then the fraction of the radioactive substance that remains after 20 years is- [I.A.S. (Pre) 1994]

Correct Answer: (d) 1/16
Solution:

37. The half-life of a radioactive substance is 10 days; it means there will be: [R.A.S./R.T.S.(Pre) 2007]

Correct Answer: (c) decay of 3/4 part of substance in 20 days
Solution:

The half life of a radioactive substance is 10 days, it means in next 10 days there will be half of the remaining radioactive substance. Thus, in total 20 days, there will be decay of 75% or 3/4 part of substance.

[(1/2) + (1/4) = (3/4)]

38. Which one of the following is not radioactive? [I.A.S. (Pre) 2001]

Correct Answer: (d) Zirconium
Solution:

Zirconium, whose atomic number is 40 is not a radioactive element. Generally, those elements whose atomic number is above 80 is considered as radioactive elements except Technetium (43) and Promethium (61).

They both are radioactive elements whose atomic number is less than 80. According to the question, Astatine (atomic number 85) and Francium (atomic number 87) are radioactive elements, while Tritium is a radioactive isotope of hydrogen.

39. Which Uranium isotope is used in nuclear power plants to produce electricity? [Uttarakhand P.C.S. (Pre) 2012]

Correct Answer: (c) U-235
Solution:

U-238 and U-235 (which has 143 neutrons) are the most common isotopes of uranium. Uranium-235 is the isotope of uranium that is used in nuclear reactors.

Natural uranium contains only around 0.7% of U-235 and most nuclear reactors require a U-235 concentration of between 3% and 5%. The process of increasing the concentration of U-235 is called enrichment.

40. Which metal can be used for producing electricity? [47ᵗʰ B.P.S.C. (Pre) 2005]

Correct Answer: (a) Uranium
Solution:

The main use of uranium in the civilian sector is to fuel nuclear power plants. 1 kg of U-235 can theoretically produce about 20 tera joules of energy which is equivalent to 1500 tons of Coal.