If a original sample of radioactive uranium-238 had a mass of 400 grams, what is the total amount of the uranium-238 sample that would be left after 9 billion years?

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.

How does the motion of particles in a gas change as the gas cools

Light waves travel than sound waves.