Answer is valence electron, they all have total of 2 valence electron.
remember group number = valence electron
Explanation:
Reaction rate is a measure of speed of a chemical reaction.
Usually, based on rates, reactions can be divided into two parts:
- Slow reactions which usually takes a long time.
- Fast reactions which takes place completely in seconds or microseconds.
Reaction rate can be defined as a change in the concentration of a reactant or product per unit time:
The unit is mol dm⁻³ s⁻¹
Reaction rate = 
The measurement of the reaction rate is based on the disappearance of a reactant or appearance of a product with increasing reaction time.
Learn more:
Reaction rate brainly.com/question/9642960
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