Which metal is present in brass,bronze and German silver?

Transition elements are usually characterised by variable oxidation states,but $Zn$ does not show this property because of:

Four successive members of the first row transition elements are listed below with their atomic numbers. Which one of them is expected to have the highest third ionization enthalpy?

The colour of an electrolyte solution depends on

The number of unpaired electrons in $Co^{2+}$ is:

German silver is an alloy of $Cu$ with