Question

A=7, B=10, C=16, D=20
(i) Identify an element having five valence electrons.
(ii) Identify an element exhibiting -2 valency.
(iii) Which of the above element is a divalent metal.
(iv) Which of the above element has stable electronic configuration
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Answer 1

Answer:

The general electronic configuration of the elements having five electrons in the outer subshell is ns2np5.This electronic configuration is characteristic of elements of group 17 i.e. hallogens and their examples are F,Cl,Br,I,At,etc.

b. The elements which have a tendency to lose two electrons must have two electrons in the valence shell. Therefore, their general configuration should be ns2. This electronic configuration is characterstic of group 2 elements, i.e. alkaline earth metals and their examples are Mg,Ca,Sr,Ba, etc.

c. The elements which have a tendency to accept two electrons must have four electrons in the valence shell. Therefore, their general electronic configuration is ns2np4. This electronic configuration is characteristic of group 16 elements and their examples are O,S,Se,Te etc.

d. A metal which is liquid at room temperature is mercury. It is a transition metal and belongs to group 12. A non-metal which is a gas at room temperature is nitrogen (group 15),oxygen (group 16),flurine, chlorine (group 17) and inert gases (group 18). A non-metal which is a liquid at room temperature is bromine

Answer 2

Explanation:

1) The elements of the group 15 (column) VA of the periodic table all have electron configurations of s2p3, giving them five valence electrons. These elements include Nitrogen (N), Phosphorus (P), Arsenic (As), Antimony (Sb), and Bismuth (Bi).

sorry but i dont know the answer of second question

3) in the attachment

4) Noble gases have stable configuration of ns2np6 with their octet completely filled which, gives them stability. Helium has exception.