Q1: The temperature at which the second Virial co-efficient of a real gas is zero is called the

ANS:A - eutectic point

The eutectic point is a critical concept in the field of chemistry, particularly in the study of phase diagrams and material science. It refers to the specific composition at which a mixture of substances undergoes its lowest possible melting point, resulting in the formation of a eutectic mixture. In simpler terms, imagine you have a mixture of two substances, let's call them A and B. At certain compositions, these substances might mix together in a way that lowers the overall melting point of the mixture compared to either substance individually. The eutectic point is the composition at which this occurs, and it represents the point at which the mixture transitions directly from solid to liquid phase at the lowest possible temperature. Understanding the eutectic point is crucial in various industrial processes, such as alloy production and soldering, where precise control over melting points is necessary. In a phase diagram, the eutectic point is typically represented as a single point where the liquid phase, solid phase of one composition, and solid phase of another composition all coexist in equilibrium.