In which reaction is a small molecule formed from the atoms removed from a single reactant molecule?
addition
condensation
elimination
substitution

Addition reaction, a chemical reaction which occurs when an atom or group of atoms is added to a molecule.

Condensation reaction is a chemical reaction that takes place when two molecules join to create a larger molecule, as it losses a small molecule.

Substitution reaction, also termed as single displacement reaction or single replacement reaction, happens when one functional group in a chemical compound is replaced or displaced by another functional group.

frequency, z, and the collision density, z, in carbon dioxide (co2), r 180 pm at 30 °c and 120 kpa

a 20-cm-long, cylindrical graphite (pure carbon) rod is inserted into an oxidizing atmosphere at 1145 k and 1.013 x 105 pa pressure. the oxidizing process is limited by the diffu- sion of oxygen counterflow to the carbon monoxide that is formed on the cylindrical surface.