Two insulated uncharged metal spheres 
and 
are placed in contact. A positively-charged rod is brought near as shown below. is then earthed momentarily. The charged rod is removed and the two spheres are then separated. Describe the charges on and . (modified)
Roughwork.
Have some mental pictures (*make drawings if you don’t have ample RAM).
First, when a positively-charged rod is brought near , charges are induced:
Notice that on surface areas and making contact, as boxed below:
the net charge is zero, 
. Hence, the plus and the minus signs (representing positive and negative charges) are erased from the drawing:
Then, is earthed momentarily:
it is convenient to treat the two spheres and as one body 
:
The process of earthing enables a transfer of negative free charges (electrons being the carrier) unidirectionally between two bodies:
here from the earth to the body, but no reversed (why?); the plus and minus signs, as boxed below:
should cancel off each other, and are thus erased from the drawing:
once the charged rod is removed:
the negative charges will be redistributed over such that the electrostatic repulsive forces between them are kept to a minimum:
after the two spheres are separated,
both spheres and will be negative charged. The descriptions go complete.
This problem is not to be attempted.