If the half life of iridium-182 is 15 years, how much of a 3 gram sample is left after 2 half-lives? A) .57 grams
B) .70 grams
C) 2.25 grams
D) .75 grams

Iwill give extra points to who gets this right

If a solution is considered basic, then a) the hydroxide ion and hydronium ion concentrations are equal. b) the hydroxide ion concentration is less than the hydronium ion concentration. c) the hydronium ion concentration is greater than the hydroxide ion concentration. d) the hydroxide ion concentration is greater than the hydronium ion concentration.

The identities of substances are the same before and after which type of change