Final answer:
The instruction is part of the tire repair process where chemical cement is applied to the inner liner of a tire, and a plug is inserted from the tire's outside into the puncture to seal it.
Step-by-step explanation:
The instruction to apply a coat of chemical cement refers to the process involved in repairing a puncture in a tire. Specifically, you would apply a chemical cement to the area around the puncture on the inner liner of the tire. After applying the cement and allowing it to become tacky, you would then insert the plug from the outside of the tire into the hole to seal it.