Answer: 
Explanation:
For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
Here iron is having an oxidation state of +3 called as 
cation and oxide 
is an anion with oxidation state of -2. Thus they combine and their oxidation states are exchanged and written in simplest whole number ratios to give neutral 
.
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
Answer:
lithium
Explanation:
this is because lithium has a valency of 1 and oxygen has a valency of 2 thereby exchanging valency to create Li²0
The answer is the troposphere
Its chemical formula H2O, indicates that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds. The hydrogen atoms are attached to the oxygen atom at an angle of 104.45°. "Water" is the name of the liquid state of H2O at standard conditions for temperature and pressure.
The correct option is FLUORINE AND COPPER.
An ionic compound is usually formed by the combination of a metal and a non metal, the metal usually act as an electron donor while the non metal act as an electron acceptor. Thus, in ionic compounds, there is total transfer of electrons from the metal to the non metal. In the question given here, copper is the metal while the fluorine is the non metal.<span />
