Question

Which of the following combination of elements is the most reactive?
(1 point)
Cs and I
K and I
Na and Br
Cs and Br

Answer 1

The reactivity of alkali metals and halogens generally increases as you go down the periodic table for alkali metals and up for halogens.

Among the combinations given:

- **Cs (cesium) and I (iodine)**: Cesium is a very reactive alkali metal, and iodine is a reactive halogen.
- **K (potassium) and I (iodine)**: Potassium is also a reactive alkali metal, but cesium is more reactive than potassium.
- **Na (sodium) and Br (bromine)**: Sodium is less reactive than both cesium and potassium; bromine is a halogen.
- **Cs (cesium) and Br (bromine)**: This combination involves a highly reactive alkali metal (cesium) and a halogen (bromine).

Considering that cesium is the most reactive alkali metal and both iodine and bromine are reactive halogens, the most reactive combination overall would be **Cs and I** or **Cs and Br**. However, cesium with iodine is generally considered to be more reactive than with bromine due to iodine being a larger and more electronegative halogen.

Therefore, the most reactive combination is **Cs and I**.