Question

1. choose the best answer. which of these element groups is most reactive, especially in water? alkali alkaline earth transition 20. choose the best answer. what is the total electron capacity for the 4th energy shell of an atom? 30 18 32 8

Explanation:

Step1: Analyze Q19 reactivity rule

Alkali metals (Group 1) have 1 valence electron, which they easily lose to react violently, especially with water, more so than alkaline earth, transition elements.

Step2: Calculate Q20 electron capacity

Use the formula for electron shell capacity: $2n^2$, where $n=4$ (4th shell).
Expression: $2\times4^2 = 2\times16 = 32$

Answer:

1. A. alkali
2. 32