Which of the following transition metal ions is colourless ?

Which one of the following transition metal ions is colourless in aqueous solution ?

Which of the following transition metal ion is not coloured?

Why do the following transition metal ions appear colourless ? Cu^(+), Ag^(+), Zn^(2+), Hg^(2+) and Cd^(2+) .

Which of the following transition metal ions has the lowest density?

Which of the following transition metal ions has the lowest density?

Which of the following transition metal ions has least magnetic moments?

Which of the following transition metal ions has highest magnetic moment ?