The largest number of stable nuclei that exist in nature have ...

[cookcarl]

The largest number of stable nuclei that exist in
  nature have
  a) both odd proton numbers and odd neutron numbers.
  b) odd proton numbers but even neutron numbers.
  c) both even proton numbers and even neutron numbers.
  d) odd neutron numbers but even proton numbers.

Question 2

After one half-life, a sample of a particular
  radioactive material
  a) is twice as massive as the original sample of material.
  b) has its half-life reduced by one half.
  c) has only half the original activity.
  d) is no longer radioactive at all.

[Ashley I]

Answer to Question 1

c

Answer to Question 2

c

[cookcarl]

Gracias!

[xthemafja]

TYSM