<span>A small proportion of helium in the crust is helium that was trapped in the Earth when the Earth formed and has not yet escaped. Most helium on Earth, however, forms as a result of alpha decay of uranium and thorium. The emitted alpha particles, once they grab a couple of stray electrons, become helium atoms and can accumulate in gas reservoirs along with things such as methane.</span>
Explanation:
A physical change is change that alters the physical properties of matter especially its form and state.
In many cases, the change is easily reversible.
Examples are change of state such as boiling, melting, freezing, condensation, sublimation e.t.c
A chemical change is one in which a new kind of matter is formed. It is always accompanied by energy changes.
Examples are combustion, rusting , precipitation, milk souring.
- Chemical changes are irreversible
- Physical changes do not lead to the formation of new kinds of matter.
- Most physical changes requires little energy.
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Answer:
Physical Properties
Explanation:
You are able to see physical properties but are unable to see chemical properties.
1.D 2.A that is pretty hard