How many atoms are in 0.75 moles of zinc

Concerning the 10.0 ml of 0.50 m nacl to 100 ml of solution: when a solution is diluted, does it change the number of moles dissolved?

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?

(apex) when a cup of water is dropped, as the cup falls, the water in the cup falls out true or false?