What is the definition of fluid friction?

Pl i beg u so much now propane burns in oxygen to produce carbon dioxide and steam. the unbalanced equation for this reaction is: c3h8 + o2 → co2 + h2o use coefficients to balance this equation. a) c3h8 + 3 o2 → 3 co2 + 4 h2o b) c3h8 + o2 → 3 co2 + 4 h2o c) c3h8 + 5 o2 → 3 co2 + 4 h2o d) 2 c3h8 + 5 o2 → 3 co2 + 4 h2o