The Law of Multiple Proportions states that if 2 elements form more than one compound between them, if the mass of one of the elements is fixed, the masses of the other element will be in a ratio of small whole numbers.
In this case, the two elements are Fe and Cl, and the 2 compounds are X and Y. Let us fix the mass of Fe in 1.00 g and analyze what happens with the masses of Cl.
For X:

For Y:

The ratio mCl in X/mCl in Y is 1.27g/1.91g = 0.664 ≅ 2/3. This is a ratio of small whole numbers, which proves the Law of Multiple Proportions.
The formula for finding the volume is Length x Width x Height. Multiply the three numbers and show your work
Explanation:
Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest halogen, and is a fuming red-brown liquid at room temperature that evaporates readily to form a similarly coloured vapour. Its properties are intermediate between those of chlorine and iodine. Isolated independently by two chemists, Carl Jacob Löwig (in 1825) and Antoine Jérôme Balard (in 1826), its name was derived from the Ancient Greek βρῶμος ("stench"), referring to its sharp and disagreeable smell.
Bromine, 35Br
The volume in liters of Hydrogen gas = 49.28 L
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Further explanation
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The reaction equation is the chemical formula of reagents and product substances
A reaction coefficient is a number in the chemical formula of a substance involved in the reaction equation. The reaction coefficient is useful for equalizing reagents and products
Reaction
2 Al (s) + 6 HCl (aq) → 2 AlCl₃ (aq) + 3 H₂ (g)
mol Al :

mol H₂ :

At STP, 1 mol =22.4 L
so the volume of hydrogen :

I think it’s A but I’m not sure, if it’s wrong I’m sorry