A box contains 2 white balls 3 black balls and 4 pink balls the number of ways in which 3 balls can be drawn  from box so that at least 1 on them is black .... plz do it using multinomial theorem

Arrange the bonds in order of increasing ionic character in the molecules: LiF, K2O, N2, SO2 and ClF3 Sol. N2 < ClF3 < SO2 < K2O < LiF Arrange the following in order of increasing ionic character: C-H, F-H, Br-H, Na-I, K-F and Li-Cl Sol. C-H < Br-H < F-H < Na-I < Li-Cl < K-F