A positively charged rod is brought near an uncharged, grounded electroscope. Which of the following statements is true?

When a positively charged rod is brought near an uncharged, grounded electroscope, the following occurs:

1. The positively charged rod induces a charge separation in the electroscope. The free electrons in the electroscope are attracted to the positively charged rod, causing them to move up towards the top of the electroscope. This leaves a net positive charge at the bottom of the electroscope.

2. Since the electroscope is grounded, the positive charges at the bottom of the electroscope are neutralized by the electrons from the ground. This leaves a net negative charge at the top of the electroscope.

3. If the positively charged rod is removed while the electroscope is still grounded, the negative charges will spread evenly throughout the electroscope, returning it to a neutral state.

4. If the ground connection is removed before the positively charged rod, the electroscope will retain a net negative charge. This is because the negative charges at the top of the electroscope are repelled by the positively charged rod and cannot return to the ground.

So, the statement that is true is: "The electroscope will have a net negative charge if the ground connection is removed before the positively charged rod."