Define Radio-activity

​(a) Define Radio-activity (2mks)

Radioactivity is the spontaneous disintegration of a nucleus releasing 
alpha, beta and gamma radiations accompanied by the release of energy

​(b) When carrying out experiments with radioactive substances the source should never be held with bare hands but with forceps. Explain? (1mk)

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​Radioactive substances are harmful to body cells when ingested 

​(i) Plot on the graph paper provided the graph of the count rate (y-axis) against time

A graph of count Rate against time(s)

​(ii) From the graph, determine the half-life of Radon-220 (1mk)

​Half-life of radon 220=54 sec + 2 (showing on graph a must)

​(e) The diagram in the figure below shows paths taken by three radiations A,B and C from a radioactive isotope through an electric field.

​(i) State the charge on plate Y (1mk)

• ​Negative

​(ii) Identify the radiations A and C (2mks)

• A- Beta particles
• B-Alpha particles 

​(iii) Give a reason why C deviates more than A (1mk)

C more massive than A

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