Science Test Questions And Answers

Explanation
Pumice is lighter than obsidian because it has little holes formed from gases escaping during the cooling process. These holes create a porous texture, reducing the overall density of the rock. In contrast, obsidian is a volcanic glass that cools rapidly without trapping any gas bubbles, resulting in a denser and heavier material.

Explanation
The correct answer explains that rocks are different from minerals because rocks are made up of minerals, but they are not crystals. This means that while minerals are naturally occurring solid substances with a specific chemical composition and crystal structure, rocks are composed of various minerals and can have different textures and compositions. Therefore, rocks can contain minerals but are not solely made up of crystals.

Explanation
The correct answer is because magma or heat and pressure would probably destroy the fossil. Metamorphic rock is formed through the process of intense heat and pressure, which can cause the organic material in fossils to be altered or destroyed. Similarly, igneous rock is formed from molten magma, which would also destroy any fossils present. Therefore, it is not likely to find fossils in these types of rocks due to the destructive nature of magma, heat, and pressure.

Explanation
The given correct answer is "Moh's Hardness Scale." This scale is used to measure the hardness of minerals. It ranks minerals from 1 to 10 based on their ability to scratch or be scratched by other minerals. Talc is the softest mineral on the scale with a rank of 1, while diamond is the hardest mineral with a rank of 10. Gypsum and calcite are also minerals that are ranked on the Moh's Hardness Scale.

Explanation
No, a smaller numbered rock cannot scratch a higher numbered rock on Moh's hardness scale. The hardness scale is based on the ability of one mineral to scratch another. A higher number on the scale indicates a greater hardness, meaning that the mineral can only be scratched by minerals with a higher number. Therefore, a smaller numbered rock would not be able to scratch a higher numbered rock.