Final answer:
For safety, welding on unknown materials should be avoided, which is true. High-voltage wires are typically not insulated, which is false. Dropping a bar magnet through a copper tube induces a current, true. Magnetic strips on credit cards should be kept away from magnets, true.
Step-by-step explanation:
The correct statement to the question 'Do not weld in anything you are unsure of what is on it or in it' is A) True. Welding on materials without knowing the substance or coating can be extremely hazardous due to potential chemical reactions.
Regarding the other queries:
- The high-voltage wires being supported by insulating connectors is B) False. These wires are usually not covered in insulating material as they are high above the ground, away from human contact, and the air gap acts as an insulator.
- If you drop a bar magnet through a copper tube, it does induce an electric current in the tube due to electromagnetic induction, which is B) True.
- It's recommended to keep credit cards with magnetic strips away from permanent magnets to prevent data loss, which makes the statement B) True.
Each question is related to safety practices and the fundamental principles of electricity and magnetism, important topics in Physics.