He put iron with sulfur and oxygen and it had a few more errors and iron is a metal the other two are nonmetals
An anion has a negative charge, while a cation has a positive charge.
I really don’t know but
Phosphorus pentoxide is a white solid which does not have any distinct odour. The chemical formula of this compound is P4O10. However, it is named after its empirical formula, which is P2O5. The molar mass of phosphorus pentoxide corresponds to 283.9 g/mol.
The coefficient of performance (cop) of a refrigerator is defined as the ratio of " the work necessary to heat or cool something usefully."
The usable heating or cooling delivered to work required ratio, also known as the coefficient of performance, or COP, of a heat pump, refrigerator, as well as air conditioning system. Higher efficiency, less energy (power) usage, and thus reduced operational costs are all related to higher COPs.
Coefficient of performance formula:

where, K = Coefficient of performance,
= heat of pumps output,
= work required by the system.
It is refrigeration's coefficient of performance (COP) will always be greater than 1.
Therefore, the coefficient of performance (cop) of a refrigerator is defined as the ratio of " the work necessary to heat or cool something usefully."
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H2O is a compound. So it's second one.