Facts about Pumice:
The lightest rock on earth.
Formed in Molten Lava.
Most of the earths crust is made from rocks such as Pumice (Igneous Rocks).
Contains many minerals that help plants to grow.
Facts about Sandstone:
It can form on land or in the sea.
It has been used as far back as prehistoric times to make house ware items and shelter contruction.
They can take thousands of years to form.
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Only the amount of gas is held constant.
Answer:
A
Chemical reaction rates vary with the conditions of the reaction, but nuclear decay rates are constant.
Explanation:
B/c chem reactions can be affected by temperature, pressure, etc. whereas, nuclear decays are constant. The decay rate itself is measured over a long period of time and it remains constant I believe.
