Answer:
Option A says we have 4 moles of Fe for each 3 moles O2
This is correct For 3 moles of O2 consumed, we need 4 moles of Fe to be reacted
Explanation:
Step 1: Data given
Step 2: The balanced equation
4Fe + 3O2 → 2Fe2O3
Step 3: Calculate the mol ratio
For 3 moles O2 we'll have 4 moles Fe
Option A says we have 4 moles of Fe for each 3 moles O2
This is correct For 3 moles of O2 consumed, we need 4 moles of Fe to be reacted
Option b says we have 2 mole Fe2O3 for each 4 moles Fe
This doesnt say anything about O2. So doesn't apply for this question.
Option C says we have 4 moles of Fe for each 2 moles Fe2O3
This is the same as option B, so doesn't apply for this question.
Option D says for each 3 moles of O2 we have 2 Fe2O3
This is true, but doesn't say anything about Fe so doesn't apply here.
Answer:
The answer to your question is letter B. 9
Explanation:
Unbalanced reaction
Al₂(SO₄)₃ + Ca(OH)₂ ⇒ Al(OH)₃ + CaSO₄
Reactants Elements Products
2 Al 1
3 S 1
14 O 7
1 Ca 1
2 H 3
Balanced reaction
Al₂(SO₄)₃ + 3Ca(OH)₂ ⇒ 2Al(OH)₃ + 3CaSO₄
Reactants Elements Products
2 Al 2
3 S 3
18 O 18
3 Ca 3
6 H 6
The sum of the coefficients is 1 + 3+ 2+ 3 = 9
The molecular formula for compound is
mass of compound is 0.670 g.
To calculate number of atoms first calculate number of moles in the compound as follows:

Molar mass of
is 283.886 g/mol, thus,

Thus, number of mole of
is 0.00236 mol.
From the molecular formula 1 mole of
has 2 mol of P (phosphorus) and 5 mol of O (oxygen).
Thus, number of moles of P and O in 0.00236 mol of
will be:

Similarly,

Now, in 1 mol of an element there are
atoms.
Number of atoms of P will be:

Similarly, number of atoms of O will be:

Total number of atoms will be sum of number of atoms of P and O:

Therefore, total number of atoms in
will be
.