Chemical compounds undergo both physical and chemical changes. which of the following is an example of a chemical change. a. salt (nacl) being dissolved into water b. heating a solid material to a liquid form c. cooling a gas into its liquid form d. combining oxygen gas and hydrogen gas to form liquid water

Covalent bond is the correct answer

The answer is atmosphere. there are four spheres of the earth: 1. geosphere (from greek word 'geo' = ground), 2. hydrosphere (from greek word 'hydro' = water), 3. biosphere (from greek word 'bio' = life), and 4. atmosphere (from greek word 'atmo' = air). a magnetosphere is a region of space around astronomical objects controlled by the magnetic field of that object. through the process of elimination, since lightning is present in the air, it can be found in the atmosphere.