16 Which change results in the formation of different substances? (1) burning of propane

(2) melting of NaCl (s)

(3) deposition of CO2 (g)

(4) solidification of water

1. The burning of propane creates different substances: propane and oxygen combine to create water and carbon dioxide:

C 3 H 8 + 5 O 2 becomes 3 CO2 + 4 H 2 O + heat

2. When NaCl melts, it is changing state, but it is still the same NaCl.

3. When gaseous CO2 deposits it is changing state, but it is still the same CO2.

4. When (presumably liquid) water solidifies, it is changing state, but it is still the same water.

So the answer is 1.