Answers

Assignment No – 1

Classification of Elements and Periodicity in Properties

Ans 1. (c) O > F > N > C. After removal of first electron the configuration of these elements is

C+ 1s2 2s2 2p1                O+ 1s2 2s2 2p3              N+ 1s2 2s2 2p2              F+ 1s2 2s2 2p4

Out of these, O has half filled p subshell so to remove e will be most difficult. O will have maximum ionization potential then C will leave their readily so as to have empty p subshell thus the potential will be least. Out of N and F, F is more electronegative than N and N is more electronegative than C thus their ionization potential will be in the same order. Thus the order will be  C) O > F > N > C

 

Ans 2.  c) Na < Mg > Al < Si. Across the period the ionization potential increases as the electron enters the same shell so the effective nuclear charge increases thus the order for Na, Al, Si is Na < Al < Si but Mg has the maximum ionization potential because its configuration is 1s2 2s2 2p6 3s2 i.e. completely filled 3s subshell thus more stable have the order is Na < Mg > Al > Si

 

Ans 3. (d)1s2 2s2 2p6 3s2

 

Ans 4. (b) Na+2 > Li+2 > Mg+2 > Be+2

 

Ans 5. (a) 0.72, 1.60

 

Ans 6. (d) Na+

 

Ans 7. (b) F- < O2- < N3-

 

Ans 8. (b) O2- > F- > Na+ > Mg2+ > Al3+

 

Ans 9. (c) Cl < P < Mg < Ca

 

Ans 10. (c) Nitrogen

 

Ans 11. (d) Fe2+

 

Ans 12. (b) The second ionization potential of Mg is greater than the second ionization potential of Na

 

Ans 13. (d) S < P < O < N