Which of the following statements about radioactivity is true? (i) Alpha particle is positively charged (ii)…

To solve this question, let’s break down the properties of the three main types of radioactive emissions:

1. Analyze the Statements

• (i) Alpha particle is positively charged: This is True. An alpha particle consists of 2 protons and 2 neutrons (a helium nucleus), giving it a charge of +2.
• (ii) Beta particle is negatively charged: This is True. A beta particle is a high-speed electron emitted from the nucleus, which carries a negative charge (-1).
• (iii) Gamma ray is neutral: This is True. Gamma rays are electromagnetic waves (high-energy photons) and carry no electrical charge.
• (iv) Beta particle has the same mass as helium atom: This is False. An alpha particle has the same mass as a helium nucleus (4 atomic mass units). A beta particle is an electron, which is extremely light (about 1/1840 the mass of a proton).
• (v) Gamma ray is charged: This is False. As established in point (iii), gamma rays are neutral electromagnetic radiation.

2. Evaluate the Options

Now, let's look at the combinations provided:

• A: i, ii, iii, iv (Includes the false statement iv)
• B: i, ii, iii (All these statements are correct)
• C: iv and v (Both of these statements are false)
• D: i, ii and v (Includes the false statement v)

3. Conclusion

Based on the analysis, statements (i), (ii), and (iii) are the only scientifically accurate descriptions of radioactive emissions. Therefore, the correct combination is i, ii, and iii.

Exam Tip: When dealing with radioactivity questions, remember the "PEN" rule for particles:

• Alpha: Heavy, positive (+2), stopped by paper.
• Beta: Light, negative (-1), stopped by aluminum.
• Gamma: No mass, neutral, stopped by thick lead.