Hydrogen
Helium
Lithium
Beryllium
Boron
Explanation:
5N right because -15N for left plus +20N for right = +5N
When it has been disproven
When children are small they are given vaccines that are usually dead viruses given to the body. These viruses don't cause damage to body and the body takes it as a real virus and prepare antibodies in the body but when a certain real disease or virus is in the body , the already presented antibodies fight with them for the protection of the body. These antibodies remain in the body so that when a disease or virus attacks the body the antibodies are already geared up to fight against them. Thus antibodies protect the body against invading microbes or viruses.
