What element has a molar mass of 30.974 g/mol

X4O10Let molar mass of X be ymolar mass = 4y + 10 x 16 = 4y+160

so, moles = 85.2 / (4y+160)

Moles of oxygen = 10 x [85.2 / (4y+160) ]Mass of oxygen = 16 x 10 x [85.2 / (4y+160) ]which is 48.0

so, 48 = 16 x 10 x [85.2 / (4y+160) ]

Solve the equation to get y.

y = 31