Pleasdseee help meee

Can someone me with 3 and 4 plz. this is for masteries test.

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

In the reaction h2co3 (aq) + 3nh3 (aq) = 2 nh4+ (aq) + co3 2-, how many electrons are transferred?