The weight of an object is minimum when it is placed at the center of the earth because when an object is in the center, it experiences gravitational pull from all directions.
* is a dereference operator & is a reference operator. They can be applied any number of times provided it is meaningful. Here p points to the first character in the string "Hello". *p dereferences it and so its value is H. Again & references it to an address and * dereferences it to the value H