Answer :
1. Valency of oxygen is 2.
=> This statement is true.
As, atomic number of oxygen is 8. So, it have 2 electrons in its first shell and 6 electrons in second or valence shell. To complete its valence shell, oxygen needs 2 more electrons to complete shell of 8 electrons. So, valency of oxygen is 2.
2. The number of atoms of each element should be same on each side of Balanced equation.
=> This statement is true.
In a balanced reaction, the number of atoms in the reactant side must be equal to number of atoms in product side. If number of atoms are equal on both sides, then we can say that the reaction is balanced.