Question 1

Which experimental result led to the rejection of the Thomson 'Plum Pudding' model of the atom?

Accepted Answer

The observation that most alpha particles passed straight through gold foil, but some were deflected at large angles.

Question 2

In the Gold Foil Experiment, what did the deflection of alpha particles indicate about atomic structure?

Accepted Answer

Atoms contain a small, dense, positively charged nucleus.

Question 3

Which nuclear decay process results in a decrease of the atomic number by 2 and the mass number by 4?

Accepted Answer

Alpha decay ($$\alpha$$ decay)

Question 4

A radioactive isotope undergoes beta decay. What happens to its atomic number and mass number?

Accepted Answer

Atomic number increases by 1; mass number remains unchanged.

Question 5

Which type of radiation is most effectively blocked by a sheet of paper?

Accepted Answer

Alpha particles ($$\alpha)$$

Question 6

What is the result of positron emission from $$^{236}_{94}Pu$$?

Accepted Answer

$$^{236}_{93}Np$$

Question 7

Which decay mode does NOT change the atomic number or mass number of the nucleus?

Accepted Answer

Gamma ray emission ($$\gamma$$ emission)

Question 8

A nucleus with too many neutrons relative to protons is most likely to undergo which type of decay?

Accepted Answer

Beta decay ($$\beta$$ decay)

Question 9

Which of the following is a real-world application of radioactivity in medicine?

Accepted Answer

Cancer detection and therapy using radioactive tracers

Question 10

What is the correct equation for the energy released in nuclear fission, according to Einstein's mass-energy equivalence?

Accepted Answer

$$E = mc^2$

Question 11

If you start with 16 g of $$^{125}I ($$half-life 59.4 days), how much remains after 178.2 days?

Accepted Answer

2 g

Question 12

Which device measures radioactivity by detecting ionization of argon gas?

Accepted Answer

Geiger counter

Question 13

Which of the following statements about nuclear fusion is correct?

Accepted Answer

Fusion combines two nuclei to form a heavier nucleus, releasing energy.

Question 14

Which unit is used to measure the absorbed dose of radiation in body tissue?

Accepted Answer

Gray ($$Gy)$$

Question 15

A nucleus with too many protons relative to neutrons is most likely to undergo which type of decay?

Accepted Answer

Positron emission or electron capture

Question 16

Which shielding material is most effective against gamma rays?

Accepted Answer

Lead

Question 17

What is the main reason alpha particles are more damaging to biological tissue than beta or gamma radiation?

Accepted Answer

Alpha particles deposit more energy over a shorter distance.

Question 18

Which decay mode is represented by the emission of a $$^{0}_{-1}e$$ particle from the nucleus?

Accepted Answer

Beta decay ($$\beta$$ decay)

Question 19

Which of the following best describes the 'island of stability' in nuclear chemistry?

Accepted Answer

A region where nuclei have the right ratio of protons to neutrons and are stable.

Question 20

Which process is used to sterilize fruit flies for pest control using radioactivity?

Accepted Answer

Radiation exposure to sterilize reproductive cells

Nuclear Chemistry: Structure, Decay, and Applications

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