Consider the reaction. 3 Mg s plus 2 cap h sub 3 PO sub 4 aq rightarrow Mg sub 3 open paren PO sub 4 close paren sub 2 s plus 3 cap h sub 2 g Which statement is true at STP? (The atomic mass of Mg is 24 point 3 1 u )

The balanced equation shows that 3 moles of Mg produce 3 moles of H₂, so the mole ratio is 1:1. At STP, each mole of H₂ occupies 22.4 L. Therefore, 3 × 24.31 g of Mg produces 3 × 22.4 L of H₂, matching the statement that 3 × 24.31 g of Mg produces 3 × 22.4 L of hydrogen gas.

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