To explain this question we need to distinct liquid, gas and solids.
Liquid means a substance or mixture which at 50°C has a vapour pressure of not more than 300 kPa, which is not completely gaseous at 20°C and at a standard pressure of 101.3 kPa, and which has a melting point or initial melting point of 20 °C or less at a standard pressure of 101.3 kPa.
Gas means a substance which at 50 °C has a vapour pressure greater than 300 kPa; or is completely gaseous at 20 °C at a standard pressure of 101.3 kPa.
Solids are the substance or mixtures that do not meet the definitions of liquid or gas.
You can easily verify the physical state of a product by checking it material safety data sheet (MSDS). Section 9 indicates whether it is liquid, solid or gas. Section 14 gives transport information including UN number and packaging group.
CurTec supplies UN-certified packaging for hazardous solids. CurTec does not supply UN-certified packaging for hazardous liquids.