Nitrate salts containing metal ions with the following electron configurations are added to
water to make a solution. Predict whether the salt solution will be colored or colorless and explain the reasoning.
a. [Kr]4d10
b. [Ar]3d3
It helps if you figure out what these elements are but isn't necessary.
a must be Cd. b must be V.
You know most salts of Cd are colorless and most V salts are colored.
But you don't need to know what they are--whether they are colored or not often depends upon the numberr of unpaired electrons, especially in the 3d orbital. Since a is 3d10 all of them are paired. b is 4d3 and all of them are unpaired.