What is the spring constant for a supermarket scale that stretches 0.01 m when a force of 4 N is applied?
N/m
What is the displacement of a spring if it has a spring constant of 10 N/m, and a force of 2.5 N is applied?

that tool would be a compass

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

if it's not useful, feel free to report for mistake in answer.

one negative thing it that it can kill water animals. another negative thing is it can cause the destruction of ecosystem. one way water pollution can be reduced is to conserve energy.