Question

determine the mass of carbon(IV)oxide,CO2,produced on burning104of ethyne,C2H2,(C=12,O=16,H=1)

Answer 1

2C2H2 + 5O2 --> 4CO2 + 2H2O

mols ethyne = grams/molar mass = ?
Convert mols ethyne to mols CO2 using the coefficients in the balanced equation. That tells you that you get 4 mols CO2 for every 2 mols C2H2.
Now convert mols CO2 to grams CO2. grams = mols x molar mass = ?

Post your work if you get stuck.