Answer : The correct option is, 13.7 mole
Solution : Given,
Moles of
= 27.4 moles
The given balanced chemical reaction is,

From the balanced chemical reaction, we conclude that
As, 2 moles of
react with 1 moles of 
So, 27.4 moles of
react with
moles of 
Therefore, the number of moles of oxygen
required are, 13.7 moles
Answer: Substance is Mercury (Hg)
number of protons = 80
number of electrons = 80
Explanation:
Atomic number which is symbolized by "Z" is the number of protons in nucleus of an atom.
Hence,
number of protons = atomic number = 80
- By knowing atomic number, we can find the element by using periodic table. Since the atomic number 80, the element is Mercury (Hg).
If the substance is in its neutral state, which means there is no charge on it, then the number of protons equals to the number of electrons of that element.
Hence,
number of electrons = number of protons = 80