$Zn$ and $Cd$ metals do not show variable valency because
they have only two electrons in the outermost subshells
their $d-$ subshells are completely filled
their $d-$ subshells are partially filled
they are relatively soft metals
Which of the following has highest ionic radii
Which of the comparison regarding $Zn,\,Cd,\,Hg$ is/are incorrect ?
$(I)$ $ZnCl_2$ is ionic whereas $CdCl_2$ and $HgCl_2$ are covalent
$(II)$ $Zn$ and $Cd$ dissolves in dilute acid $(HCl)$ liberating $H_2$ but $Hg$ can not
$(III)$ $Zn$ and $Cd$ forming with ppt. of $Zn(OH)_2$ and $Cd(OH)_2$ but $Hg$ forms coloured ppt. of
$(IV)$ all from $A_2^{2+}$ type ion
Which of the following order is not correct
Many transition metals form interstitial compounds. The characteristics of these interstitial compounds are
$(I)$ They have high melting points, higher than those of pure metals
$(II)$ They are very hard
$(III)$ They retain metallic conductivity
$(IV)$ They are chemically more reactive than the pure metals
Which ion is not coloured