Don't put too much baking soda when making a cake. Only put as much baking soda as it says.
Baking soda causes specific chemical reactions to occur when it is mixed with other ingredients and baked. CO2 is produced, and this is what causes cakes to rise and taste light and fluffy.
You might have the oven too hot.
the purpose of baking powder in a cake is to make it rise and not make it flat and if you put too much of baking powder your cake might burst in the oven/microwave what ever you use
Vinegar
Baking powder is a leavening agent, which is what causes the cake to rise. Too little baking powder will cause the cake to be tough and compact, and won't rise as expected.
Baking powder is not a gas, but it does make a cake rise by releasing carbon dioxide into the batter through chemical reaction.
to make it rise and be less dense
It's not the milk alone that makes a cake rise. If the recipe includes milk it probably also contains either baking powder and/or baking soda. This combination of a base (Baking soda or Baking Powder) and an acid (milk) causes a slight chemical reaction which causes the cake to rise.
Self raising flour makes the cake rise, but if you don't have any you can use plain flour and baking powder which has the same effect. 225g plain flour and 4 teaspoons baking powder, will transform it into self raising flour.
to make it 'rise', have air pockets, not be dense
It depends on the type of cake. If you are making a sponge cake where the mixing method involves whipping the eggs and sugar, and then folding in the flour and butter, then it will be fine. The whipping created bubbles which will rise in the oven - baking powder will give it additional rise, but it is not vital.
They will rise and not be as gooey. (More cake-like in result).
It either helps whatever you're baking rise or make whatever you're baking soft and fluffy.
Yes because yeast is added to make the cake rise.