Q1: Orifice-meter is used to measure

ANS:B - discharge

An orifice meter is primarily used to measure the discharge of fluid flowing through a pipe. It measures the rate of flow of the fluid passing through it. The orifice meter consists of a flat plate with a hole (or orifice) in it. The pressure difference across the orifice is used to calculate the flow rate of the fluid based on Bernoulli's equation and other principles of fluid mechanics. While an orifice meter does involve the measurement of pressure differences, it is not used specifically to measure the pressure at a point. Instead, it utilizes pressure differences to determine the discharge or flow rate. Therefore, the correct answer is discharge.