Question

The mass of $\beta$-particles when they are emitted is higher than the mass of electrons obtained by other means. $\beta$-particle and electron, both are similar particles.

• A. Both assertion and reason are true and reason is the correct explanation of assertion
• B. Both assertion and reason are true but reason is not the correct explanation of assertion
• C. Assertion is true but reason is false
• D. Both assertion and reason are false

Answer 1

Answer: (B)

Both assertion and reason are true but reason is not the correct explanation of assertion

Answer 2

$\beta$-particles are emitted with very high velocity (up to 0.99 c). So, according to Einstein's theory of relativity, the mass of a $\beta$-particle is much higher compared touts rest, mass $(m_0)$. The velocity of electrons obtained by other means is very small compared to c (velocity of light). so, its mass remains nearly $m_0$.