Question

1 which represents a chemical reaction? (1 point) hydrogen burning steam forming on a window crushing stones ice melting 2 what does the word element best describe? (1 point) a mixture all matter a substance that cannot be broken down a pure substance

Explanation:

1. A chemical reaction results in the formation of new substances. Hydrogen burning is a chemical reaction as hydrogen reacts with oxygen to form water. Steam forming on a window is condensation (a physical - state change), crushing stones is a physical change in shape, and ice melting is a phase change from solid to liquid, all of which are physical changes.
2. An element is a substance that cannot be broken down into simpler substances by chemical means. A mixture is a combination of two or more substances, all matter is a broad term, and a pure substance can be an element or a compound.

Answer:

1. A. hydrogen burning
2. C. A substance that cannot be broken down