Caffeine's molecular formula is c8h10n4o2. the molar mass of caffeine is 194g/mol. what is the percentage of carbon in caffeine

The molecular formula of Caffeine is C₈H₁₀N₄O₂
the mass of 1 mol of caffeine - 194 g
In 1 mol of caffeine, mass of C is - 12 x8 = 96 g
Since 1 mol - 194 g, in 194 g of caffeine there's 96 g of Carbon
To find the mass percentage of C 
Mass percentage = Mass of Carbon / mass of caffeine  x 100% 
                            =  96 g / 194 g x 100 
                            = 49.5 %
49.5 % of caffeine is composed of C.