Final answer:
The volume of residual gas after cooling is 5cm³ of O₂.The correct answer is option B.
Step-by-step explanation:
To determine the volume of residual gas after cooling, we need to calculate the volume of the product of the reaction between hydrogen and oxygen. The balanced chemical equation for this reaction is:
2H₂(g) + O₂(g) → 2H₂O(g)
From the equation, we can see that 2 volumes of hydrogen react with 1 volume of oxygen to produce 2 volumes of water vapor. Therefore, for every 1 volume of hydrogen, we need 0.5 volumes of oxygen. Since we have 10 cm³ of hydrogen and 20 cm³ of oxygen, we can calculate:
10 cm³ H₂ x 0.5 cm³ O₂ / 1 cm³ H₂ = 5 cm³ O₂
So, the volume of residual gas after cooling is 5cm³ of O₂.The correct answer is option B.