Q1: The centre of pressure of a vertical plane immersed in a liquid is at

ANS:D - none of these.

The "none of these" option indicates that none of the provided options accurately describes the location of the center of pressure of a vertical plane immersed in a liquid. In reality, the center of pressure of a vertical plane immersed in a liquid is not necessarily located at the centroid of the area, the center of the higher edge, or the center of the lower edge. The precise location of the center of pressure depends on various factors, including the shape of the immersed object, the distribution of pressure forces over its surface, and the depth of immersion. For a vertical plane immersed in a liquid, the center of pressure can be determined based on the pressure distribution acting on the surface of the plane. This pressure distribution is influenced by factors such as the shape of the object, the density of the fluid, and the depth of immersion. The center of pressure is typically located below the centroid of the area for a vertical plane immersed in a liquid. It can vary depending on the shape of the immersed object and the distribution of pressure forces acting on its surface. Therefore, in this case, "none of these" accurately describes the location of the center of pressure of a vertical plane immersed in a liquid, as its precise location depends on various factors and cannot be determined solely based on the options provided.