Q1: In order to avoid capillary correction, the minimum diameter of a manometer used for measuring pressure, should be

ANS:C - 6 mm

A diameter of 6 mm for a manometer tube is considered sufficient to avoid significant capillary effects and the need for capillary correction in many practical applications. Capillary effects arise due to the surface tension of the liquid in the manometer tube. When the diameter of the tube is very small, surface tension forces become relatively more significant, causing the liquid column in the tube to deviate from the expected behavior based solely on pressure differences. By using a larger diameter tube, such as 6 mm, the influence of surface tension effects is reduced, and capillary correction becomes less significant. In many cases, a 6 mm diameter tube can provide accurate pressure measurements without the need for additional corrections. However, it's important to note that the suitability of a 6 mm diameter tube depends on various factors, including the properties of the fluid being measured, the required accuracy of the pressure measurement, and the specific conditions of the measurement setup. Therefore, while 6 mm can be a suitable diameter for many practical applications, the choice of tube diameter should be made based on the specific requirements and considerations of each individual measurement scenario.