Answer:
Pair 1 : ( F , Br )
Pair 2 : ( Li , K )
Pair 3 : ( P , As )
Step-by-step explanation:
Following the groups (column number ) in the periodic table (since elements that belong to the same group exhibit similar properties ) we can build the following pairs:
Pair 1 : ( F , Br ) → Since both belong to the Halogens group ( Group number 17)
Pair 2 : ( Li , K ) → Since both belong to the Alkali metals group ( Group number 1)
Pair 3 : ( P , As ) → Since both belong to the Pnictogens group ( Group number 15)