Final answer:
To make the reaction more exothermic, we need to consider factors that affect the stability of the products and the energy released. A large radius for M²⁺, low ionization energy for M, increasing bond energy for the halogen, decreasing electron affinity for the halogen, and increasing size of the anion formed by the halogen will all make the reaction more exothermic.
Step-by-step explanation:
In order to make the reaction more exothermic, we need to consider the factors that affect the stability of the products and the energy released during the reaction. Here are the explanations for each option:
(a) A large radius for M²⁺ will make the reaction more exothermic. A larger radius leads to a higher polarizability, meaning that the metal ion can better distort the electron cloud of the halogen molecule, resulting in a stronger bond and a more exothermic reaction.
(b) A low ionization energy for M will make the reaction more exothermic. A lower ionization energy means that it is easier to remove an electron from the metal, allowing it to form a more stable and exothermic bond with the halogen.
(c) An increasing bond energy for the halogen will make the reaction more exothermic. A stronger bond between the halogen atoms makes it harder to break, releasing more energy when the metal forms a bond with the halogen.
(d) A decreasing electron affinity for the halogen will make the reaction more exothermic. A lower electron affinity means that the halogen is less likely to accept an electron, allowing the metal to form a more stable bond and release more energy.
(e) An increasing size of the anion formed by the halogen will make the reaction more exothermic. A larger anion can better stabilize the positive charge of the metal cation, leading to a stronger and more exothermic bond.