What is ‘baking powder’? How does it make the cake soft and spongy?

What is ‘baking powder’? How does it make the cake soft and spongy?
Answer:
Baking powder is a mixture of baking soda (NaHC03) and an edible acid like tartaric acid.
Baking powder on heating produces carbon dioxide gas which causes bread or cake to rise making it soft and spongy.
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