The screening effect of 'd' electrons is:

1. Much less than s-electrons.

2. Much more than s-electrons.

3. Equal to s-electrons.

4. Equal to p-electrons.

The electronegativity of elements from group 1 to group 17 :

1. Decreases

2. Increases

3. Remains constant

4. All of the above

Match list-I with list II and select the correct answer using codes given below:

1. List-I Ions                                List-II Radius (in pm)

(I) Li⁺                                         (a) 216

(II) Na⁺                                      (b) 195

(III) Br^-                                      (c) 60

(IV) I^-                                        (d) 95

     Codes:

      I   II   III   IV

1.   a   b    d    c

2.   b   c    a    d

3.   c   d    b    a

4.   d   c    b    a 

The screening effect of d-electrons is :

1. Equal of the p-electrons

2. Much more than p-electrons

3. Same as f-electron

4. Less than p-electrons 

Z_eff of Na⁺ and Na⁰ are respectively-

1. 1.95 and 1.22

2. 0.85 and 0.35

3. 1 and 0.35

4. 6.85 and 2.2

The order of screening effect of electrons of s, p, d and f orbitals of a given shell of an atom on electrons in its outer shell is :

1. s > p > d > f

2. f > d > p > s

3. p < d < f < s

4. f > p > s > d