All energy types start with what crucial object

Calcium hydride (cah2) reacts with water to form hydrogen gas: cah2(s) + 2h2o(l) → ca(oh)2(aq) + 2h2(g) how many grams of cah2 are needed to generate 45.0 l of h2 gas at a pressure of 0.995 atm and a temperature of 32 °c?

What is the empirical formula of a compound that is 50.7% antimony and 49.3% selenium ?

If i had 2 m naoh solution, what does the 2 m stand for? 2 molar, but 2 of a solute in 1