A physical change doesn't change what the substance is but for chemical change a new substance is formed and energy is either given off or absorbed.
Answer:
1.C+2H2-CH4
Explanation:
when we add two to hydrogen the product is equal to the reactant
<span>Actually Igneous rocks are classified either based on grain size or
based on mineralogy. However grain size is clearly not a chemical property. So
we can say that they are classified chemically based on mineralogy or the
abundance of quartz or silica present.</span>
