1.A chemical change is different than a physical change because in a chemical change a. Chemicals are used

b. Molecules do not physically touch

c. A new substance is formed and in a physical change no new substance is formed

d. The change can be seen but in a physical change it cannot

2.Which of the following is a physical change?

a. Burning

b. Freezing

c. Rusting

d. Oxidation

3.Jamal combined baking soda and vinegar, but he is having trouble determining if what he observed is a chemical reaction or a physical change. Choose two answers that demonstrate evidence of a chemical change?

a. Change in color

b. Absorption of heat

c. No change on properties

d. Formation of new substances

4. In a chemical reaction, if the reactants are heated, the reaction usually happens

a. Faster

b. Slower

c. At the same rate

d. In a smaller volume

Explain why your answer is correct:

answer; i believe the correct answer is (117);

question - in 1827, john walker, a druggist in a small english town, tipped a splint with sulphur, chlorate of potash, and sulphid of antimony, and rubbed it on sandpaper, and it burst into flame. the druggist had discovered the first friction-chemical match, the kind we use to-day. it is called friction-chemical because it is made by mixing certain chemicals together and rubbing them. although walker's match did not require the bottle of acid, nevertheless it was not a good one. it could be lighted only by hard rubbing, and it sputtered and threw fire in all directions. in a few years, however, phosphorus was substituted on the tip for antimony, and the change worked wonders. the match could now be lighted with very little rubbing, and it was no longer necessary to have sandpaper upon which to rub it. it would ignite when rubbed on any dry surface, and there was no longer any sputtering. this was the phosphorus match, the match with which we are so familiar. according the paragraph what was the benefit of the new phosphorus match? it burst into flame when rubbed on sandpaper. it was made by mixing chemicals. it could be ignited on any dry surface. it threw fire in all directions.

answer - matches required natural chemicals