At STP, a 12,0-liter sample of CH4(g) has the same total number of molecules as 1
6.0 L of H2(g) at STP
2
120 L of CO2(g) at STP
3
18.0 L of HCI(g) at STP
24.0 L of O2(g) at STP

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In the acetylene torch, 7.5 moles of O₂ are needed to react with 3.00 moles of acetylene gas C₂H₂.

Explanation: -

The balanced chemical equation for this reaction is

2 C₂H₂ + 5 O₂ → 4 CO₂ + 2 H₂O

From the equation we see

2 moles of C₂H₂ react with 5 moles of O₂

3.00 moles of C₂H₂ react with x 3.00 moles of C₂H₂

= 7.5 moles of O₂

Thus, in the acetylene torch, 7.5 moles of O₂ are needed to react with 3.00 moles of acetylene gas C₂H₂.