Q1: The starting of a car takes time in winter, because the

ANS:C - vaporisation of the fuel is decreased.

The starting of a car takes time in winter primarily because the vaporization of the fuel is decreased. In colder temperatures, the vaporization of fuel becomes more challenging. Fuel needs to vaporize before it can combust effectively in the engine's cylinders. When temperatures drop, the fuel may not vaporize as readily, leading to incomplete combustion and difficulty in starting the engine. While the pour point of fuel decreasing might seem like a logical option, it actually refers to the temperature at which a fuel begins to solidify, becoming wax-like. This phenomenon affects the flow of fuel rather than its ability to vaporize. The octane number of the fuel decreasing wouldn't directly affect the starting of a car in winter. Octane number relates more to the fuel's resistance to knocking or pinging in the engine, which is a different aspect of combustion. Fuel supply for ignition being insufficient might be a factor in starting issues, but it's usually not the primary reason. However, if fuel lines or filters are frozen due to extremely low temperatures, it could indeed lead to insufficient fuel supply for ignition.