Solutions

  1. How are stationary waves formed? > Stationary (or standing) wave: when two progressive waves of the same wavelength and amplitude travelling with the same speed through a medium in opposite directions and superimpose upon each other, they give rise to a wave which is called stationary wave. In stationary wave, there are certain points where the amplitude of vibration is always zero. These points are known as nodes. Midway between these nodes, there are other points when amplitude of vibration is maximum. These points are known as antinodes. The formation a stationary wave along with nodes and antinodes is shown in figure,…  2. If you are walking on the moon surface, can you hear the cracking sound behind you? Explain. >There is no atmosphere on the moon because of its weak gravity. For the propagation of sound waves, medium is necessary. This means sound waves cannot propagate through vacuum. So, due of lack of medium (i.e. atmosphere), the propagation of sound w...

                                   Questions  and Answers 1. How would you confirm that B in BF 3 gets sp 2 Hybridization? > The central atom Boron has one half filled orbital in ground state (1 s 1 2 s 2 2px 1 2py 0 2pz 0 ) but it has          three half filled orbital in excited state since one electron is promoted from 2s to 2p orbital during chemical combination.       Hence, one 2s and two 2p orbital undergo sp 2 hybridization to form three Sp 2 hybrid orbital of equivalent energy and identical shape & size which takes trigonal planer geometry with bond angle 120 0 .     Each half filled sp 2 hybrid orbital of boron overlaps with half filled 2p z orbital of three fluorine atom to form three covalent bonds. 2. C in C 2 H 2 gets sp hybridization, why? >Each carbon has two half filled orbitals i...