Out of `Co^(2+)`, `Zn^(2+)` and `Cu^+(2+) which will give aqueous coloured solution ?

Out of the ions Ni^(2+) , Zn^(2+) and Cu^2+) , which will give coloured aqueous solution and what will be the magnetic beghaviour of each ion ? (Atomic number of Ni = 28, Zn =30 and Cu = 29).

Out of the ions Ag^+ , Co^(2+) and Ti^(4+) which will give coloured aqueous solution and what will be the magnetic behaviour of each ion ? (Atomic number of Ag = 47, Co = 27 and Ti = 22).

Out of ions Co^(2+) ,Cr^(3+), ( Sc^(3+) which will give coloured aqueous solution and what will be the magnetic behaviour of each ion ? (Atomic number of Co = 27, Sc = 21 and Cr = 24).

Out of Co^(2+) and Zn^(2+) which will be paramagnetic and why ?

Out of Cu^(2+) and Cu^(+) ion, which one is colourless and why?

HgCl_2 and SnCl_2 cannot exist in aqueous solution. Why ?

Out of Ag^+ and Co^(2+) which one will be coloured and why? (Atomic number of Ag is, 47 and Co is 27).

Out of Cu^+ and V^+2 which will be coloured and why ? (Atomic number Of V is 23 and Cu is 29).

Which of the following ions does not give coloured solution ?