which of the following combinations of elements is the most reactive?

Question

Na and Br
Cs and Br
Cs and I
K and I

Answer 1

The reactivity of alkali metals (such as Na, K, and Cs) with halogens (like Br and I) generally increases down the group for alkali metals. This means that cesium (Cs) is more reactive than potassium (K) and sodium (Na). Similarly, bromine (Br) is more reactive than iodine (I) because it is higher in the group of halogens.

Based on this information, the combination that would be considered the most reactive would be Cs and Br. Cesium is the most reactive alkali metal from the options given, and bromine is more reactive than iodine.