How many moles are there in 2.35x10^23 molecules of water

What are the percent by mass of copper in penny lab

Which step in naming unsaturated hydrocarbons is used for alkenes but not alkynes

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.