all of the amino acids found in proteins have a carboxyl group and an amino group bonded to the same carbon atom except

It would be (at) + cu (s)

Answer (b) supersaturation;

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.

Aquantity of that isotope to decay to 1/2 of  its original value