Q1: In forced circulation, the heating element is injected

ANS:A - internally

In forced circulation, the heating element is typically injected internally. Here's why: Forced circulation systems involve the use of a pump to circulate the fluid through the heating element and the system. The heating element, which may be a coil or a set of tubes, is usually immersed within the fluid. The pump then forces the fluid to flow through the heating element, where it absorbs heat before being circulated to the desired location. Therefore, the heating element is injected internally into the fluid stream to facilitate heat transfer, making option (a) "internally" the correct choice.