15 extra multiple-choice questions for Nuclear Physics (10th Standard Science, Samacheer Kalvi), beyond the ones printed in the textbook — each with the correct option highlighted and a clear, worked explanation. Free to read in English and Tamil.
Q1
Who discovered artificial or man-made radioactivity in the year 1934?
- A. Henri Becquerel
- B. Irene Curie and F. JoliotCorrect
- C. Marie Curie and Pierre Curie
- D. Ernest Rutherford
Explanation. Artificial radioactivity was discovered by Irene Curie and F. Joliot in 1934 by bombarding lighter elements like boron and aluminium with alpha particles.
Q2
Which of the following elements has an atomic number less than 82 but undergoes spontaneous natural radioactivity?
- A. Uranium
- B. Radium
- C. PromethiumCorrect
- D. Polonium
Explanation. Uranium, radium, and polonium have atomic numbers greater than 82. Promethium, with an atomic number of 61, is one of only two identified radioactive substances with an atomic number less than 82.
Q3
One Rutherford (Rd) is defined as the quantity of a radioactive substance which produces how many disintegrations per second?
- A. \(3.7 x 10^10\)
- B. \(10^6\)Correct
- C. 1
- D. \(3.7 x 10^4\)
Explanation. One Rutherford (Rd) is defined as the quantity of a radioactive substance which undergoes \(10^6\) disintegrations in one second.
Q4
What is the charge of a beta particle as defined in nuclear physics?
- A. Positive charge of +2e
- B. Negative charge of -eCorrect
- C. Neutral (zero charge)
- D. Positive charge of +e
Explanation. Beta particles are basic elementary particles present in all atoms, which are electrons and possess a negative charge of -e.
Q5
According to Soddy and Fajan's displacement laws, what happens to the atomic number and mass number of a daughter nucleus formed during alpha decay?
- A. Mass number decreases by 4, atomic number decreases by 2Correct
- B. Mass number decreases by 2, atomic number decreases by 4
- C. Mass number remains same, atomic number increases by 1
- D. Mass number increases by 4, atomic number increases by 2
Explanation. When a radioactive element emits an alpha particle, a daughter nucleus is formed whose mass number is less by 4 units and atomic number is less by 2 units.
Q6
In which type of radioactive decay does only the energy level of the nucleus change, while both the atomic number and mass number remain the same?
- A. Alpha decay
- B. Beta decay
- C. Gamma decayCorrect
- D. Neutron decay
Explanation. In a gamma decay, only the energy level of the nucleus changes. The atomic number and mass number of the radioactive nucleus remain the same.
Q7
In 1939, which scientists discovered that a heavy uranium nucleus splits into smaller nuclei of comparable mass when bombarded with neutrons?
- A. Henri Becquerel and Marie Curie
- B. Otto Hahn and F. StrassmanCorrect
- C. Soddy and Fajan
- D. Irene Curie and F. Joliot
Explanation. In 1939, German scientists Otto Hahn and F. Strassman discovered that uranium breaks up into two smaller nuclei when bombarded with neutrons, known as nuclear fission.
Q8
What is the average energy released in a single nuclear fission process of a uranium-235 nucleus?
- A. About 200 MeVCorrect
- B. About 20 MeV
- C. About 2 MeV
- D. About 2000 MeV
Explanation. The energy released in a single nuclear fission process is about 200 MeV, which is equivalent to \(3.2 x 10^-11\) Joules of energy.
Q9
What is the term used to describe radioactive elements that are not fissionable on their own but can be converted into fissionable materials?
- A. Fissile materials
- B. Fertile materialsCorrect
- C. Moderators
- D. Coolants
Explanation. Radioactive elements that can be converted into fissionable materials are called fertile materials. Examples include Uranium-238, Thorium-232, and Plutonium-240.
Q10
Which principle is utilized in the design of an atom bomb to create a massive explosion?
- A. Controlled chain reaction
- B. Uncontrolled chain reactionCorrect
- C. Controlled nuclear fusion
- D. Spontaneous alpha decay
Explanation. The atom bomb is based on the principle of an uncontrolled chain reaction, where neutrons and fission reactions multiply geometrically, releasing enormous energy.
Q11
Which atomic bomb dropped during World War II utilized a plutonium core?
- A. Little Boy
- B. Fat ManCorrect
- C. Kamini
- D. Apsara
Explanation. The atomic bomb dropped over Nagasaki, Japan, was called 'Fat Man' and utilized a plutonium core, whereas 'Little Boy' dropped over Hiroshima used uranium.
Q12
What is the temperature range required to execute a nuclear fusion process, giving it the name thermonuclear reaction?
- A. \(10^3\) to \(10^5 K\)
- B. \(10^5\) to \(10^7 K\)
- C. \(10^7\) to \(10^9 K\)Correct
- D. \(10^9\) to \(10^11 K\)
Explanation. Nuclear fusion is possible only at extremely high temperatures of the order of \(10^7\) to \(10^9 K\) and high pressure to push nuclei closer.
Q13
Which of the following radioisotopes is used in medicine to diagnose and treat anemia?
- A. Radio-phosphorous (P32)
- B. Radio-iron (Fe59)Correct
- C. Radio-iodine (I131)
- D. Radio-cobalt (Co60)
Explanation. Radio-iron (Fe59) is used to diagnose and treat anemia. Radio-phosphorous is used for skin diseases, radio-iodine for goiter, and radio-cobalt for cancer.
Q14
Which materials are commonly used as moderators in a nuclear reactor to slow down fast neutrons?
- A. Boron and Cadmium rods
- B. Uranium and Plutonium
- C. Graphite and Heavy waterCorrect
- D. Liquid sodium and Helium
Explanation. Moderators slow down high-energy neutrons to provide slow neutrons. Graphite and heavy water are the commonly used moderators.
Q15
Who was the first chairman of the Indian Atomic Energy Commission, which was established in August 1948?
- A. Dr. A.P.J. Abdul Kalam
- B. Dr. Homi Jahangir BhabhaCorrect
- C. Dr. Vikram Sarabhai
- D. Dr. Raja Ramanna
Explanation. Dr. Homi Jahangir Bhabha was the first chairman of the Indian Atomic Energy Commission, established in August 1948 by the Department of Indian Scientific Research.
Frequently asked questions
How many MCQs are there in Nuclear Physics?
This chapter has 15 book-back multiple-choice questions, each with the correct answer and a step-by-step explanation.
Are these 10th Standard Science MCQs free to practise online?
Yes. Every question, answer and explanation here is free, and you can also take them as a timed practice test.
Where can I find the Nuclear Physics book-back answers?
The correct option for each question is highlighted on this page with a worked explanation, plus a quick answer-key summary at the top.
