C.
What is the total mass of carbon in 33 g of ibuprofen?

              24.97 g of C

Explanation:

Molar Mass of Ibuprofen is 206.29 g/mol

Molecular Formula of Ibuprofen is C₁₃H₁₈O₂

Also, 13 C atoms has mass of 12.01 × 13 = 156.13 g

Percentage of C in Ibuprofen,

% age of C = 156.13 / 206.29 × 100 = 75.68%

Now calculate 75.68 % of 33 g as,

75.68 % = x / 33 g × 100

x = 75.68 × 33 / 100

x = 24.97 g of C

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.