Question

which set of elements is in order from least to most valence electrons?
o a) ca, k, cl, ar
o b) k, as, br, kr
o c) ne, f, o, b
o d) c, b, be, li

Explanation:

Step1: Find valence electrons for each element in option B

• For \(K\) (Potassium), valence electrons \(= 1\)
• For \(As\) (Arsenic), valence electrons \(= 5\)
• For \(Br\) (Bromine), valence electrons \(= 7\)
• For \(Kr\) (Krypton), valence electrons \(= 8\)

Step2: Check the order

The order \(1 (K)<5 (As)<7 (Br)<8 (Kr)\) is from least to most valence electrons.

Step3: Check other options (for completeness)

• Option A: \(Ca\) (2 valence electrons), \(K\) (1), \(Cl\) (7), \(Ar\) (8). Order is \(K < Ca
• Option C: \(Ne\) (8), \(F\) (7), \(O\) (6), \(B\) (3). Order is \(B
• Option D: \(C\) (4), \(B\) (3), \(Be\) (2), \(Li\) (1). Order is \(Li

Answer:

B. \(K, As, Br, Kr\)