Which of the following are pure substances ? Will give brainliest !!!

How would the number of moles (n) of o2 change if the atmospheric pressure doubled but all other variables stayed the same

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.

Which of these features are formed when hot groundwater is forced out through cracks in the earth's surface?