Radioactivity - Questions on Half-life

Half-life of a radioactive nuclide is the time taken for half the nuclei of that nuclide in any sample to decay.

(time taken for the count rate/mass/nuclei/atoms to fall to half of its original value)

Quick revision on half-life. 2002SPP1Q19, 2003SPP1Q19, 2006SPP1Q20, 2004SPp1Q19

Questions:

Answer: Option C

Answer: Option C

Answer: Option C

Answer: Option C

Answer: Option D

Answer: Option C

Answer: Option C

Answer: Option B

Answer: Option D

Answer: Option D

Copper spheres P and Q, P has larger volume. What quantity is the same? 2020PP01q7

This question is very straight forward. As both P and Q are copper, the density will be the same. But many are unsure of KE. Let look at how to prove that KE is different.

Answer: Option A

What happens to frequency and speed of water wave as it goes to shallow region? 2019PPp1q23

Once the wave is produced, the frequency remains constant. Hence speed V of the wave is directly proportional to the wavelength of the wave.

Answer: Option C