Which electrons in an atom take part in chemical bonding and what are they called

The electrons in an atom that take part in chemical bonding are the electrons in the outermost shell and they are called valence electrons.

Explanation: An atom is composed of three particles: protons, neutrons and electrons. The protons and neutrons occupy the centrally located nucleus while the electrons are located in the empty space outside the nucleus. Electrons are distributed around the nucleus in paths called electron shells. The electrons in the outermost electron shells are called the valence electrons. The valence electrons are the electrons that participate in chemical bonding. During chemical bonding, the valence electrons are either transferred from one atom to another or the valence electrons are shared between two atoms. A type of chemical bonding in which there is a complete transfer of valence electrons from an atom of a metal to an atom of a non-metal so that can attain octet or duplet structure of noble gases is called electrovalent or ionic bonding. A type of chemical bonding in which there is sharing of electrons between two atoms of non-metals so that both can attain the octet or duplet structure of noble gases is called covalent bonding.

option a is correct i.e.

explanation:

in context to the membrane of nerve impulse, the outer membrane of neuron is semi permeable that is only sodium ions can pass through the membrane i.e. smaller ions can pass through the membrane while larger ions cannot pass through it.