Question 15 there are three sets of sketches below, showing the same pure molecular compound (hydrogen chloride, molecular formula hcl ) at three different temperatures.

According to the temperature, the molecules of a substance behave differently. The boiling point of HCl is -85.05 °C and the melting point is -114.2 °C.
Therefore, if the temperature is kept above  -85.05 °C, the molecules will be spaced widely apart and will be in the gaseous state, exhibiting its properties.
If the temperature is between -114.2 °C and -85.05 °C, the molecules will be arranged in layers capable of slipping over one another because they will be in the liquid state.
Finally, if the temperature is below -114.2 °C, the molecules will be arranged in an orderly manner because they will be in the solid state.