Which of the following results in a chemical change in matter?

1. baking powder is a 1: 1 molar mixture of cream of tartar (khc4h4o6) and baking soda (nahco3). a recipe calls for two teaspoons (a total of 8.0 grams) of cream of tartar. how much baking soda must be added for both materials to react completely?

The speed of light is around 6.706×10^8 miles per hour. what is the speed of light in units of miles per minute?

Calculate the number of molecules present in 0.750 mol of mgo.