Which of these are chemical reactions? check all that apply. a. baking bread b. cutting up vegetables for a salad c. mashing potatoes d. setting off fireworks

The answer is A and D.

Chemical reactions are where new substance is produced as 2 or more substances are reacted together. This process usually requires heat or electricity.

For A, when baking bread, yeast is respired anaerobically and releases carbon dioxide and ethanol. New substances are formed and therefore its a chemical reaction.

In B, the vegetables are cut up, but nothing new is formed. There's no reaction between vegetables and another substance. Therefore it's not a chemical reaction.

For C, this is similar to B. Again, the potato is mashed but they didn't add or produce anything new. So it's not a chemical change

And for D, fireworks is basically when you burn the gunpowder and some metal pieces. Fire is reacted with the powder and metal and produces new substance such as sparks or smoke. So this is a chemical reaction.

Explanation:

you have to keep heat and pressure rising on the rock, until the minerals melt. The earlier stages of this process (if it ends at that point) are called 'migmatite' (mixed rock) where the rock consists partially of unmelted metamorphic rock