I really need help on this Chemistry Problem

Please, I really need help on this

1. baking powder is a 1: 1 molar mixture of cream of tartar (khc4h4o6) and baking soda (nahco3). a recipe calls for two teaspoons (a total of 8.0 grams) of cream of tartar. how much baking soda must be added for both materials to react completely?

What does x represent in the formula for the compound xcl4?

Which of the following is always a reactant in a combustion reaction? oxygen nitrogen hydrogen carbon