The atomic mas of Oxygen gas is 32 g/mol
The molar mass of B2H6 IS 27.66 g/mol
Therefore, a mass of 106.3 g of B2H6 will contain;
106.3/27.66 = 3.843 moles
The mole ratio of B2H6 : O2 is 1: 3
Therefore, moles of oxygen will be 3.843 ×3/1 = 11.529 moles
Therefore, the mass of liquid oxygen needed would be;
11.529 × 32
= 368.94 g