1.1. The three states of matter are solid, liquid and gas.

What is the name of the change of state when a liquid changes into a solid?

1.2. A gas was left to cool to form a liquid.

Figure 1 shows how the temperature of the substance changed with time. 

Figure 1

From A to B the substance is a gas. From C to D the substance is a liquid.

i) State the time when the gas first started to form a liquid. 

(1) ............................ minutes 

ii) Calculate the number of minutes it took from the gas first starting to form a liquid until the substance was completely liquid.  

(1)

............................ minutes 

1.3. Figure 2 shows the melting points and boiling points of four substances, W, X, Y and Z. 

Figure 2

Using the information in Figure 2

i) give the letter of the substance that is a solid at 20 °C

(1)

ii) give the letter of a substance that is a liquid at 50 °C 

(1)

1.4. The diagrams below show particles in five different structures. The different circles show different particles. 

Draw one straight line from each substance to its structure.