Question

Elements A, B and C have atomic numbers 17, 19 and 10 respectively.
State which one is:
i) A non-metal
ii) A metal
iii) Chemically inert.

• A. A -> Metal
  B -> Non-Metal
  C -> Chemically inert
• B. A -> Chemically inert
  B -> Metal
  C -> Non-Metal
• C. A -> Non-Metal
  B -> Metal
  C -> Chemically inert
• D. A -> Metal
  B -> Chemically inert
  C -> Non-Metal

Answer 1

The correct option is C

A -> Non-Metal
B -> Metal
C -> Chemically inert

Electronic configurations of A, B and C are as follows:
A (Z = 17) : 2, 8, 7
B (Z = 19) : 2, 8, 8, 1
C (Z = 10) : 2, 8
i) Elements with 4 to 7 electrons in their outermost shell are non-metals. Hence A is a non-metal.
ii) Elements with 1 to 3 electrons in their outermost shell are metals. Hence B is a metal.
iii) Elements with 8 electrons in their outermost shell are noble gases and hence chemically inert. Thus C is chemically inert.