Which of the following pairs of Base-Source are correctly matched?

Ammonium Hydroxide - Window cleaner

The correct answer is option 3. Ammonium Hydroxide - Window cleaner.

The correct pair of Base-Source among the options provided is Ammonium Hydroxide - Window cleaner.

Ammonium hydroxide is commonly found in household window cleaners, often referred to as "ammonia-based" cleaners. It acts as a base in these cleaners.

The other options do not match correctly:

1. Calcium Hydroxide (slaked lime) is not typically used in soap; it's more commonly used in agriculture, wastewater treatment, and construction.

2. Sodium Hydroxide is not found in milk of magnesia; rather, it's magnesium hydroxide that is the active ingredient in milk of magnesia, used as an antacid or laxative.

4. Magnesium Hydroxide is commonly used in the production of lime water, but it's not the substance found in it. Lime water is a saturated solution of calcium hydroxide (not magnesium hydroxide).

So, the correct answer is 3. Ammonium Hydroxide - Window cleaner