In view that 1 molecule of ammonia contains 3 hydrogen atoms, i believe your working is correct!

Keep Learning,

Sean Chua
Master Trainer & Author

Something not right with your Chemical Formulae of Lead (II) Nitrate.

As such, your balanced chemical equation and ionic equation is incorrect.

Regards,
Sean Chua

Q: how many atoms of hydrogen are there in 0.75 moles of ammonia?
Ans:
no. of molecules of ammonia = 0.75*6.02*10^23
no of atoms of hydrogen = 3*0.75*6.02*10^23
=1.35*10^24

is it correct?

im not a teacher but still i guess i can tell you about it…………

when we say about 1 mole of a substance, we mean to mention its 6.02 X 10 power 23 particles of it………………….

so for one atom i-e one particle of it first we should find its moles by dividing 1 by the avogadro’s number i-e 6.02 X 10 power 23………….

then by simple formula of moles= mass/molar mass

mass= molar mass X moles

we know the molar mass of calcium = 40
and (calculated) moles of one atom of calcium = 1.661129568106312292358803986711 power negative 24

then by multiplying 40 by the mole number

40 X 1.661129568106312292358803986711 = 6.6445182724252491694352159468439 power negative 23 grams……

hope you did not felt humiliated

as for the balanced equation:-

PbCO3(s) + HNO3(aq) ——> PbNO3(aq) + CO2(g) + H2O(l)

for the spectator ions:-
NO3 (-1) aq

the equation would be

PbCO3(s) + H (+1)(aq) —–> Pb (+2)(aq) + CO2(g) + H2O(l)