Question 1:

Which reaction mechanism involves the replacement of an atom or group by another atom or group?

Explanation: The reaction mechanism that involves the replacement of an atom or group by another atom or group is called "Substitution."

Question 2:

In which reaction mechanism is a molecule split into two or more smaller molecules?

Explanation: The reaction mechanism in which a molecule is split into two or more smaller molecules is called "Elimination."

Question 3:

Which reaction mechanism involves the addition of atoms or groups to a molecule?

Explanation: The reaction mechanism that involves the addition of atoms or groups to a molecule is called "Addition."

Question 4:

Which type of substitution reaction involves the simultaneous exchange of two atoms or groups between two molecules?

Explanation: The type of substitution reaction that involves the simultaneous exchange of two atoms or groups between two molecules is called "Nucleophilic substitution."

Question 5:

In which type of elimination reaction does a base abstract a proton from a molecule to form an alkene?

Explanation: The type of elimination reaction in which a base abstracts a proton from a molecule to form an alkene is called "E2 (Bimolecular elimination)."