Why baking powder if it does exactly what baking soda does?

    lemonBaking soda reacts as soon as it comes in contact with the acidic ingredient (lemon juice, vinegar etc) and carbon dioxide is formed instantaneously and it's critical that the batter has to be baked immediately before the gas escapes. That's when baking powder comes into picture because we have the option of delaying the gas producing reaction. The batter doesn't have to be baked immediately.