What is the correct formula for iron(III) oxide?

Fe 3+

Explanation:

iron is Fe and it's 3 and has positive

Fe2O3

Explanation:

the roman numeral tells you the charge of the metal, and you know oxygen is -2 charge so you need the least common multiple of +3 and -2 so that they cancel out, which is 6 so you need 2 of the +3 and 3 of the -2

whats the meaning of /

as given the equation is

2al + 6 hcl > 2 alcl3 + 3 h2(g)

as per equation two moles of aluminum reacts with six moles of hcl to give two moles of alcl3 and three moles of hydrogen gas

given: three moles of al are present and 7 moles of hcl

for three moles of aluminum nine moles of hcl will be required

however as 7 moles of hcl are present so the limiting reagent is hcl

hcl is going to decide the number of moles of product formed

when six moles of hcl are present = 3 moles of h2 are formed

when one mole of hcl is present == 3/6 mole sof h2 will be formed

when 7 moles of hcl are present = 3 x 7/ 6 moles of h2 will be formed = 3.5 moles of h2