Answer: 10.2 grams
Explanation:
The balanced chemical reaction is :

According to the ideal gas equation:

P = Pressure of the gas = 740 torr = 0.97 atm (760torr=1atm)
V= Volume of the gas = 12.0 L
T= Temperature of the gas = 19°C = 292 K 
R= Gas constant = 0.0821 atmL/K mol
n= moles of gas


According to stoichiometry:
2 moles of hydrogen are generated by = 1 mole of 
Thus 0.48 moles of hydrogen are generated by =
moles of 
Mass of 
Thus 10.2 grams of
are needed to generate 12.0 L of hydrogen gas if the pressure of hydrogen is 740. torr at 19°C
1. Atomic weight of fluorine
2. Number of proton and neutrons found in the nucleus of the element
3. And every number uniquely identifies each of the the elements
<span>2Fe2O3(s) + 3C(s) →4 Fe(s) + 3CO2(g)
3 mol 3mol
4 mol x mol
x=4*3/3= 4.0 mol
</span>2Fe2O3(s) + 3C(s) →4 Fe(s) + 3CO2(g)<span>
2 mol 3 mol
14 mol x mol
x=14*3/2= 21.0 mol</span>