Q1

Q1 Sacred Ileart Sr. Sec. School, B.R.S Nagar, Ltld TEST YOUR KNOWLEDGE TRY Class- Xl How would you explain the that the first ionization enthalpy ofLi is smaller than Be. while the second ionization enthalpy (IF?) of Li is much greater than for Be? State the periodic law of Mendeleev. Whv this law had to be revised subsequently • After Ca. electrons enter in 4s orbital befoæ going to .3d orbital. But when a transitiOn metal ionizes, the 4s electrons are removed first. Why'? 3 224. (a) Elements A. B, C and D have atomic numbers 12, 19' 29 and 36 respectively. On the basis of electronrc configuration, write to which group of the periodic table each element belongs. (b) Predict the blocks to which these elements can be classified. Also predict their periods and groups. . Nitrogen has positive electron gain enthalpy whereas oxygen has negative. However, oxygen has lower ionization enthalpy than nitrogen. Explain. 6. How does the metallic and non metallic character vary on moving from left to right in a period? Among alkali metals which element do you expect to be least electronegative and why? 8. Draw the Lewis structure of SF6. PCI„ 1127. Mention shapes. 9. Arrange H20. NI-13. CHA in the decreasing order Of bond angle. Explain the reason. 10. Explain why N2 has greater bond dissociation energy than whereas 02 has lesser bond dissociation energy than 02 • I l. Discuss and compare the trend in ionization enthalpy of the elements Of group I with those of group 1 7 elements. 12 _ BeF2 molecule is linear while SF2 is angular though both are triatomic. 13. XeF2 molecule is linear molecule but it is sp d hybridized . Why? 14. Explain why o-hydroxy benzaldehyde is liquid at room temperature while p-hydroxy benzaldehyde is high melting solid. 15. Why does formic acid exist as dimer? What is its consequence? 16. Compare the relative stability of the 10110wing species and indicate their magnetic properties: 02, 02', 02'. ()22•. 7. O- nitro phenol and p- nitro phenol, discuss hydrogen bonding among these molecules. 18. How many sigma and pi bonds are present in naphthalene? I Why is pyramidal while BF3 is triangular planar, though both are tetra atomic zount for the linear shape of 13' ion.