Question 7

6 2 (iv) [Xe] 4f 5d 6s 6. The statement that is not correct for periodic classification of elements is: (i) The properties of elements are periodic function of their atomic numbers. (ii) Non metallic elements are less in number than metallic elements. (iii) For transition elements, the 3d-orbitals are filled with electrons after 3p-orbitals and before 4s-orbitals. (iv) The first ionisation enthalpies of elements generally increase with increase in atomic number as we go along a period. 7. Among halogens, the correct order of amount of energy released in electron gain (electron gain enthalpy) is: (i) F > Cl > Br > I (ii) F < Cl < Br < I (iii) F < Cl > Br > I (iv) F < Cl < Br < I 8. The period number in the long form of the periodic table is equal to (i) magnetic quantum number of any element of the period. (ii) atomic number of any element of the period. (iii) maximum Principal quantum number of any element of the period. (iv) maximum Azimuthal quantum number of any element of the period.