iv- A gas mixture containing 21% O2 and 79% N2 flows through a pipe of circular cross-section of diameter 2cm at atmospheric pressure. The velocity of O2 is 0.04m/s and N2 is 0.035m/s. What is the value of molar average velocity (m/s) of the mixture? a) 0.036 b) 0.035 c) 0.034 d) 0.033

Crude oil being produced from a well is known to be a mixture of 30% water and 70% oil by volume. This mixture is stored in a vertical cylindrical tank and allowed to separate into a lower water layer and upper oil layer. The tank is vented to the atmosphere on top and the gauge pressure at the bottom of the tank is measured to be 87,000 Pa. Take the density of the water to be 998 kg/m³ and that of the oil to be 840 kg/m 3. Find the heights of the individual layers of water and oil in meters, i.e. hwater and hoil shown below. P oil vent water air h oil h water