Is a freeze plug responsible for loud knocking and stalling of an engine?

No, a freeze plug is not responsible for loud knocking and stalling of an engine. Freeze plugs are used in most engines to protect the block and cylinder head from damage caused by freezing temperatures. They are designed to pop out when the water inside the engine freezes, allowing the water to expand without causing damage. A loud knocking noise and stalling of the engine are more likely caused by issues such as worn or damaged engine bearings, connecting rods, or pistons.