Which alloy contains non metal

The magnetic moment of a transition metal compound has been calculated to be $3.87$ $B.M.$ The metal ion is

Which of the following element has maximum density

The correct order of decreasing third ionisation enthalpy of $Ti,\, V,\, Cr,\, Mn$ is

Choose an Incorrect match of colour of compounds 

Cuprous ion is colourless while cupric ion is coloured because