Question

oil floats on top of water. this means that oil is ____ dense than water.
more
less

sodium and chlorine chemically combine to form table salt. this makes salt a
mixture
compound
element
atom

according to the law of conservation of mass, if i start with 10 grams of water, how much water will i end up with if i boil it in an enclosed system?
10 g
1 g
20 g
5 g

Explanation:

1. Less dense substances float on more dense substances. Since oil floats on water, oil is less dense than water.
2. When two or more elements chemically combine, they form a compound. Sodium and chlorine combine to form table - salt (sodium chloride), so salt is a compound.
3. The law of conservation of mass states that in a closed system, mass is neither created nor destroyed. Boiling water in an enclosed system only changes its state from liquid to gas, but the mass remains the same. Starting with 10 grams of water, you will end up with 10 grams of water.

Answer:

1. B. less
2. B. compound
3. A. 10 g