Substances like liquid mercury are very , but substances like rubber are very

electrons form the atoms f one material may move to the atoms of the other material. The movement of electrons from one atom to another changes the charge of the atoms. When an atom loses electrons, it is left with more protons than electrons, so it then has a positive charge. when an atom gains electrons, it has more electrons than protons so its charge is negative.

Explanation:

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.