Question

why solid co2 is called dry ice

Answer 1

Solid carbon di oxide is known as dry ice because it looks like ice and because when it melts (it actually sublimes)it goes from solid to gas, no liquid, hence dry ice.

Answer 2

solid co2 i.e solid carbon dioxide is called dry ice because it looks same white colour as a ice looks and another reason is that it doesn't change into liquid state it directly sublimes and changes into gaseous form .