Which among the following elements is a soft element as compared to others?

What is the characteristic valence shell electronic configuration of the elements of group $11$?

What metals are in German silver alloy?

What is the number of elements present in each series of transition elements?

Which of the following metal ions is colourless?

If the colours of salts of transition elements are due to the presence of unpaired electrons in the transition metal ions,which of the following ions will be colourless in aqueous solution? (The atomic numbers of $Ti$ and $Fe$ are $22$ and $26$ respectively.)