A charged rod carrying a negative charge is brought near two spheres that are in contact with each other but insulated from the ground. If the two spheres are then separated, what kind of charge will be on the spheres?

The sphere near the charged rod will be positive while the other sphere will be negative.

Explanation:

Due to electrostatic charges on the two spheres, which are uniformly distributed, that is they have equal number electron and proton uniformly distributed.

When a negatively charged rod is brought near the two spheres, the electrons on the sphere which is in direct contact with the negatively charged rod will be repelled leaving only proton which is positively charged. Also the repelled electrons move into the second sphere and this second sphere becomes negative due to excess electron in it.