Define decay constant in Radioactivity.

Define decay constant of a radioactive sample. Which of the following radiations, alpha-rays, beta -rays, gamma -rays are easily absorbed by matter?

Define decay constant of a radioactive sample. Which of the following radiations, alpha-rays, beta -rays, gamma -rays travel with greatest speed?

Define decay constant of a radioactive sample. Which of the following radiations, alpha-rays, beta -rays, gamma -rays are similar to X-rays?

Define decay constant of a radioactive sample. Which of the following radiations, alpha-rays, beta -rays, gamma -rays are similar in nature to cathode rays?

Define rate constant (k).

Define the term half life period and decay constant of a radioactive substance. Write their SI unit. Establish a relation between them.