Year 9: Molecules and Matter

The particles in a gas have _______ energy than the particles in solids or liquids.

• More

• Less

What happens to the pressure of a gas when the volume of the container increases?

• The pressure of the gas increases.

• The pressure of the gas stays the same.

• The pressure of the gas decreases.

What happens to the gas molecules when the volume of the gas container decreases?

• The gas molecules hit the container surface more often.

• The gas molecules hit the container surface the same.

• The gas molecules hit the container surface less often.

Steam machines are used to sterilise kitchen work surfaces.

Calculate the energy needed to change 0.06 kg of water into steam.

The latent heat of vaporisation for water is 2 260 000 J/kg.

Use the correct equation from the Physics Equations Sheet.

Give your answer in kJ.

Put the statements in order to correctly identify how to correctly identify the density of an irregular shaped object.

A - To calculate the density use the equation density = mass / volume

B - Place the dry object on the balance and record the mass in kg.

C - Carefully lower the object into the water

D - Tie a piece of cotton around the object

E - Measure and record the amount of water displaced into the measuring cylinder

• B - C - D - E - A

• B - D - E - C- A

• B - D - C - E - A

Calculate the density of the metal cube shown in the diagram. The mass of the cube in 16.8 kg.

Which is the correct unit of density?

• m³/kg

• kg/m²

• kg/m³

• kg.m²

A plumber uses a blowtorch to melt a 0.5 kg bar of soft solder whilst

making a lot of solder joints.

Calculate the amount of energy transferred by the blowtorch, after the

solder has reached the melting point, to melt the bar of soft solder.

Give your answer in kilojoules.

Use the correct equation from your notes or the inside cover of your exercise book.

The latent heat of fusion of soft solder is 45 000 J/kg.

The 0.5 kg of soft solder gradually solidifies to make solid joints in the copper pipes.

Calculate the amount of energy released by the solder joint when it cools from 180 °C to 25 °C.

The specific heat capacity of solder is 210 J/kg °C.

Which is the correct unit for specific heat capacity?

• C/J/km^o

• kJ/kg^oC

• kJ/g^oC

• J/kg^oC