4 A metal wire of length 1cm and of uniform diameter has a resistance 0.8ohms. What is the resistance of a 50 cm. wire coil made of the same material but having twice it's diameter.

None of the above. Resistance is directly proportional to length, inversely proportional to cross-sectional area. Pay attention in class, and observe that even easy multiple choice questions can have only wrong answers if the setter makes a mistake.