• Explain the following statements.
           (a)    The first ionization energy of sodium is
                (i)    less than that of magnesium.
                    …………………………………………………………………………………
                    …………………………………………………………………………………
                    …………………………………………………………………………………
                    …………………………………………………………………………………
               (ii)    greater than that of potassium.
                    …………………………………………………………………………………
                    …………………………………………………………………………………
          (b)     The electronegativity of chlorine is higher than that
                    of sulfur.
                    ……………………………………………………………………………………….
                    ……………………………………………………………………………………….
                    ……………………………………………………………………………………….
                    ……………………………………………………………………………………….
Ans :
(a)   
(i)    Na has lower nuclear charge/number of protons;
electrons being removed are from same energy level/shell;
or Na has larger radius/electron further from nucleus;   
Award this mark if both electron arrangements are given.

(ii)    Na electron closer to nucleus/in lower energy level/
Na has less shielding effect;
Allow counter arguments for Mg in (i) and K in (ii).

(b)    chlorine has a higher nuclear charge;
attracts the electron pair/electrons in bond more strongly;   

  • The compounds Na2O, Al2O3 and SO2 respectively are 
        A.    acidic, amphoteric and basic.       
        B.    amphoteric, basic and acidic.
        C.    basic, acidic and amphoteric.
        D.    basic, amphoteric and acidic.
        (Ans : D )