When the elements in group 1 are considered in order from top to bottom, each successive element at standard pressure has
Aa higher melting point and a higher boiling point.
Ba higher melting point and a lower boiling point.
Ca lower melting point and a higher boiling point.
Da lower melting point and boiling point.
Aa higher melting point and a higher boiling point.
Ba higher melting point and a lower boiling point.
Ca lower melting point and a higher boiling point.
Da lower melting point and boiling point.