Dear Student,
Blue litmus can be turn red only by an acid.
According to pH scale the substance which have pH from 0 to 6 are consider acid and the substance which have pH 8 to 14 are consider base or alkaline. The substance that have pH 7 are consider neutral. The pH of baking powder is 9 that means it is a base. So baking powder will not turn blue litmus red.
Regards