Question

which of the following combination of elements is the most reactive? (1 point) na and br cs and i cs and br k and i

Explanation:

Step1: Analyze metal reactivity

In the alkali metal group (Group 1), reactivity increases down the group. The order of reactivity for the metals in the options is \(Cs > K>Na\). Cesium (\(Cs\)) is more reactive than potassium (\(K\)) and sodium (\(Na\)) because as we move down the group, the outermost electron is further from the nucleus and easier to lose.

Step2: Analyze non - metal reactivity

In the halogen group (Group 17), reactivity decreases down the group. The order of reactivity for the non - metals in the options is \(Br > I\). Bromine (\(Br\)) is more reactive than iodine (\(I\)) because as we move down the halogen group, the ability to gain an electron (electronegativity) decreases.

Step3: Determine the most reactive combination

Combining the most reactive metal (\(Cs\)) with the more reactive non - metal (\(Br\)) among the given pairs will give the most reactive combination. So, the combination of \(Cs\) and \(Br\) is the most reactive.

Answer:

C. Cs and Br