Which of the following is true about radiometric dating?

W) All parent material in a mineral is converted to the daughter product

X) When the quantities of parent and daughter products are equal, two half-lives have transpired

Y) The number of radioactive atoms that decay during one half life is always the same

Z) The percentage of radioactive atoms that decay during one half life is always the same
Z) THE PERCENTAGE OF RADIOACTIVE ATOMS THAT DECAY DURING ONE HALF LIFE IS ALWAYS THE SAME