<span>In general mutations often occur during nuclear division because each chromosome has to replicate before division (mitosis). During replication your 3 billion nucleotides make copies of themselves leaving one copy in the original cell and another in the sister cell after division. This as you can imagine makes mutations most likely to occur here.
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A chemical change is a change in which the composition of the matter is changed at the molecular level, most chemical changes are not easily irreversible, for example, an egg being cooked, the egg changes from its liquid like state to a solid, and it is not possible to revert it back to its original change. The egg itself is changed in this case.
A physical change on the other hand however, is only changing the substance of a matter, not its composition, this is usually easily reversible. For example, water turning into ice, the water's substance changed from its liquid state to its solid state, it is still water, and it can easily be turned back into water by heating it.
Sorry for the long explanation,
Hope this helps!
Answer:
Water,mineral salts and carbon dioxide
