26) B
Let us first write down the reaction equation.
2Na + 2H2O –> 2NaOH + H₂
We have the Mr of Sodium = 23 and its mass = 0.23g
Moles = Mass / Mr = (0.23 / 23) = 0.01 mol
Molar ratio (Na : H) = 2 : 1
So moles of hydrogen gas produced = 0.01 / 2 = 0.005 mol
Volume of 1 mole of gas at room temperature = 24 dm³
So volume of 0.005 mol of gas = (24 x 0.005) = 0.12 dm³
