Question

rocks are solids that are made of minerals. for example, schist is a rock that may contain the minerals muscovite, chlorite and talc, among others. obsidian may contain hematite, biotite and other minerals, too. while minerals are pure substances, rocks are not. not every piece of schist will contain the same minerals bonded in the same way. think of rocks like cookies with chocolate chips, oatmeal, raisins and walnuts. minerals are like the ingredients in those cookies: the flour, the sugar, the chocolate, oats, raisins and nuts. not every cookie will have the same ingredients even if youre using the same batter. thats why rocks arent pure substances. theyre mixtures. you cant see every ingredient in a cookie. likewise, you cant always see every mineral that makes up a rock. thats why we can observe and measure minerals to identify them, but its harder to do the same for rocks.
rocks are
choose one option
a are always pure substances.
b made up of different substances.
c edible like cookies.
d always made of the same minerals bonded the same way.

Explanation:

The text states that rocks are made of minerals (which are pure substances), but rocks themselves are not pure substances. It also compares rocks to cookies with various ingredients (different substances), indicating that rocks are made up of different substances. Option A is incorrect as rocks are not pure substances. Option C is wrong because rocks are not edible. Option D is incorrect as the text says "Not every piece of schist will contain the same minerals bonded in the same way".

Answer:

B. made up of different substances.