Apascal is a unit for measuring pressure. which of the following is equal to a pascal unit?

The answer for #3 is c but i don't know why

How many grams of co(g) are there in 74.5 ml of the gas at 0.933 atm and 30o c?

Achemistry student weighs out 0.306 g of citric acid (h3c6h5o7), a triprotic acid, into a 250 ml volumetric flask and dilutes to the mark with distilled water. he plans to titrate the acid with 0.1000 m naoh solution. calculate the volume of naoh solution the student will need to add to reach the final equivalence point. be sure your answer has the correct number of significant digits.