HELP! pH = -log10[H+]. If pH 3.5 what is [H+]?

This active feature of earth's crust in building mountain ranges as well as islands. this feature is a a) cavern. b) earthquake. c) mountain. d) volcano.

If you add 10ml of hot water to 10ml of cold water and the change in tempature 8°c calculate how much energy is gained by the cold water

Afusion reaction takes place between carbon and another element. neutrons are released, and a different element is formed. the different element is a) lighter than helium. b)heavier than helium. c)the same weight as helium. d)dependent on the element that reacted with carbon.