What is the trend of enthalpy of formation of alkali metal fluoride?

Explanation

To determine the trend of the enthalpy of formation of alkali metal fluorides, we need to analyze how various factors change as we move down the group in the periodic table from lithium to cesium. Here’s a step-by-step solution:

### Step 1: Identify the Alkali Metal Fluorides
The alkali metals include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs). Their corresponding fluorides are:
- Lithium fluoride (LiF)
- Sodium fluoride (NaF)
- Potassium fluoride (KF)
- Rubidium fluoride (RbF)
...