Water. Has a PH volume of 0. Dissolve in most substances, is made of helium and oxygen.

How do convection currents form underwater mountains?

:calculate the sum of the interior angles of a 13-sided polygon.

Brian's school locker has a three-digit combination lock that can be set using the numbers 5 to 9 (including 5 and 9), without repeating a number. the probability that the locker code begins with a prime number is %. the probability that the last digit of the locker code is an odd number is %.