28) Calculate the effective nuclear charge for valence shell electron of Br atom:

29) The atomic number of 3 elements A, B and C are x, x+1 and x+2. C is an alkali metal. In a compound of A and C, the nature of bond is:

30) Which of the following relations is correct?

31) Find out the value of Z_eff for Nitrogen:

32) The IE of Li is 520 kJ⁄mol. The amount of energy required to convert 70 mg of Li atoms in gaseous state into Li⁺ ions is: