When an atom of lithium loses an electron, the atom becomes a
1. negative ion with a radius smaller than the radius of the atom
2. negative ion with a radius larger than the radius of the atom
3. positive ion with a radius smaller than the radius of the atom
4. positive ion with a radius larger than the radius of the atom

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.

it's c. elements are placed in rows based on how may valencies electrons have.