Answer is: mass of water is 1,35 grams.
Chemical reaction: 2H₂ + O₂ → 2H₂O.
m(H₂) = 9,5 g.
n(H₂) = m(H₂) ÷ M(H₂).
n(H₂) = 9,5 g ÷ 2 g/mol.
n(H₂) = 4,75 mol.
m(O₂) = 1,2 g.
n(O₂) = 1,2 g ÷ 32 g/mol.
n(O₂) = 0,0375 mol; limiting reactant.
From chemical reaction: n(O₂) : n(H₂O) = 1 : 2.
n(H₂O) = 0,0375 mol · 2 = 0,075 mol.
m(H₂O) = 0,075 mol · 18 g/mol.
m(H₂O) = 1,35 g.
