You go to the store and get some. Other than yeast, there is no substitute for these ingredients to make things rise.
A different answer:
What you can do depends on the recipe. Some cakes use the air in beaten egg whites to "lift" the batter, but these cakes tend to be delicate and require some skill in baking. Similarly, there are a number of cookies such as meringues that use only egg whites for loft. There are other cookies or "confections" that do not use any leavening. Shortbread and stove-top chocolate drop cookies are two examples. In the bread category, it is possible to make a "sponge" of only flour, sugar and water, then allow that to sit in the open air to make a starter for sour dough. Otherwise, you are left to make some sort of flat bread or unleavened bread such as matzoh.
It wont rise.
Yes you can use self raising flour for churros
You can use self raising flour, wholemeal flour or wholemeal self raising flour or even yeast.
It is best to use self-raising flour if the recipe asks for it, as it is not the same as plain flour, but you can substitute plain flour for self-raising flour provided you add raising agents like baking powder and bicarbonate of soda yourself to the flour.
you use self-raising flour so that when the cake is cooking it rises and it adds to the mixture you use too make a cake :)
You can but you need to add baking powder and salt to it.
No
The question is not clear. "On its own" suggest no other ingredients, which would result in nothing but self-raising flour.
yes you can use self raising flour but before you bake it you should make holes on it with a fork
you dont have to use a raising agent like bicarb
If you were baking a cake: Self-Raising Flour - would make it rise Plain Flour - wouldn't make it rise People use self-raising in cakes to make them bigger, but they use plain in pancakes so it keeps it thin.
Yes, self-raising flour will help make the muffins rise, while plain flour won't unless you add baking powder to the muffins.