What is the mass of 7.2x1020 molecules of CH4?

What is conserved in the reaction shown below? h2(g) + cl2 (g) --> 2hcl(g)a. mass onlyb. mass and moles onlyc. mass, moles, and molecules onlyd. mass, moles, molecules, and volume

How many moles of co2 are produced during the complete combustion of 3.6 moles of c2h6

Abaker touches a pie right after taking it out of the oven. which statement best explains why the pie feels hot?