Answer is: R - Formed by adding 5 g of sugar to 1 L of water.
Sugar and water make a homogeneous mixture (the same proportions of its components throughout any given sample).
Boiling pure water is physical change of substance (from liquid to gaseous state).
Combining three hydrogen atoms to every nitrogen atom is chemical reaction (new substance is formed): 3H₂ + N₂ → 2NH₃.
Compressing carbon under high pressure is physical change.
