The poly atomic ion formula for ammonium would be NH4+
The letter (d.) strong base or acid would be the most appropriate answer to the question above. An indicator is a strong base or acid. Indicators are strong base and acid because through this you can determine if a compound is acid or base with its color.
The given balanced reaction is,

The stoichiometric coefficients of each element or compound represents the number of moles of that element or compound required for the complete reaction to take place.
The mole ratios of different products and reactants will be:



So the mole ratio comparing iron (Fe) and oxygen gas (
) is
4 : 3
multiply by 100.4.36×10-5cm