Question

Four elements V,W,X,Y and Z along with their electronic configuration are given below:

Elements

Electronic configuration

2,1

W

2,2

X

2,3

Y

2,4

Z

2,5

a) Which one of the above element is a gas? (1 mark)

b) Which one of the element is the smallest in the above period?( 1 mark)

c) i) Which one of the above element can form a large number of covalent compounds? ii) The element Z belongs to which group and which period? (2 marks)

OR

i) State the modern periodic law of classification of elements

ii) On moving from left to right in the period What happens to the number of valence electrons? (2 marks)​

Answer 1

V, W, X, Y and Z are Li, Be, B, C and N respectively (For reference only)

Answer:

a) Z is a gas

b) Z

c) i) Y. ii) Z belongs to group 15 and period 2

OR

i) Modern Periodic Law states that the chemical and physical properties of elements are a periodic functions of their atomic number.

ii) On moving from left to right, the number of valence electrons increase