Why is radioactivity dangerous? explain?

If the radioactive source is outside the body: Alpha radiation is not as dangerous because it is unlikely to reach living cells inside the body. Beta and gamma radiation are the mostdangerous sources because they can penetrate the skin and damage the cells inside

H tricky one let me think and get back to u

Radon-222 or rn-222 has a half-life of 3.82 days. to determine the fraction of an original sample of rn-222 that remains unchanged after 7.646 days, we calculate the amount of rn-222 remaining after 7.646 days and divide it with the original amount. using 1 gram as a basis and using half-life calculation methods, we can determine that  0.249 or 0.25  grams of rn-222 will remain, and thus the fraction remaining is 0.25 or 1/4.