Li, Na, K F, Cl, Br
A. Li and F
B. Li and Br
C. K and F
D. K and Br
Answer:C
Li, Na, K F, Cl, Br
A. Li and F B. Li and Br C. K and F D. K and Br
Explanation: because potassium (k) and flourine (F) react with most other elements while other pair of options do not as compared to it. In Group 1 chemical reactivity increases down the group and in Group 17 florine is most reactive as its bond braking energy if very low.