Which is the correct sequence of transferring heat through convection?
1. As a result, the heated part becomes less dense or lighter.
2 The colder air above us is denser and heavier so it goes
down and pushes the hot air upward.
3 The cold air is pushed upward by colder heavier air above. In
this way, the entire liquid or gas becomes evenly heated.
4 When liquid or gas is heated the molecules of the heated part
move faster and faster away from each other.​

There are two steps in the usual industrial preparation of acrylic acid, the immediate precursor of several useful plastics. in the first step, calcium carbide and water react to form acetylene and calcium hydroxide: cac2 (s) + 2h2o (g) → c2h2 (g) + caoh2 (s) =δh−414.kj in the second step, acetylene, carbon dioxide and water react to form acrylic acid: 6c2h2 (g) + 3co2 (g) + 4h2o (g) → 5ch2chco2h (g) =δh132.kj calculate the net change in enthalpy for the formation of one mole of acrylic acid from calcium carbide, water and carbon dioxide from these reactions. round your answer to the nearest kj .