3rd Group Cation (Al=3, Cr+3, Fe+3) || 4th Group Cation (Mn+2, Zn+2,Ni+2, Co+2) || 5th Group Cation (Ba+2, Cr+2, Ca+2) || 6th Group Cation (Mg+2)

2nd group Cation (Hg+2, Pb+2, Cu+2, Cd+2, Rn+3)

Of the ions Zn^(2), Ni^(2 +) and Cr^(3 +) [atomic number of Zn = 30, Ni = 28, Cr = 24 ]

Which of the two cations Mg^(2+) and Al^(3+) is smaller?

Arrange giving reason the following elements in increasing order of their atomic size : (a) Be, O, F (Given that they beiong to 2nd, 16th and 17th groups respectively and to 2nd period). (b) I, CI, F (Given that they belong to 5th, 3rd and 2nd periods respectively of 17th group). (c) Mg, N, P (Given that Mg and P belong to 2^(nd)" and "15^(th) group respectively of 3^(rd) period and N belongs to 15^(th)" group of "2^(nd) period).

Of the ions Zn^(2+),Ni^(2+) and Cr^(3+) (atomic number Zn=30,Ni=28,Cr=24):

To avoid the precipitation of hydroxides of Ni^(2+),Co^(2+),Mn^(2+) along with those of the third group cations, the solutions should be: