1) First we calculate the molecular mass of the substance:
C₆H₁₂O₆
Molar mass of C: 12 g/mol
Molar mass of H: 1 g/mol
Molar mass of O: 16 g/mol
(6 x 12) + (12 x 1) + (6 x 16) = 72 + 12 + 96 = 180 g/mol
2) Now just use rules of three to figure out the percentage of hydrogen:
180 ----- 100%
12 ----- x %
180x = 12 × 100
x = 1200/180
x = 6.67%
Answer: The % composition of Hydrogen for C₆H₁₂O₆ is 6.67%.