If you make an electromagnet using a battery circuit and a steel nail, how can you increase its magnetic strength?
a. replace the nail with a copper rod
b. wrap more coils of wire around the nail
c. use a longer nail
d. remove the plastic insulation from the wire coil

The correct answer is B. wrap more coils of wire around the nail. This is how you can increase its magnetic strength. Thank you for posting your question. I hope this answer helped you. Let me know if you need more help. 

Answer;

B.wrap more coils of wire around the nail

Explanation;Electromagnets are made by winding a wire through a magnetic material such as soft iron core making a coil, and then passing electric current through the coil thus making the soft iron core magnetic.The strength of the electromagnet depends on the number of coils and also the size of the electric current through the coil.Therefore, in this case wrapping more coils of wire around the nail increases the strength of the electromagnet.

Is it b the answer and yes

The characteristics of groundwater is said to be: are weak turbiditya constant temperaturechemical composition and almost overall absence of oxygen.