Solutions | Starter Quiz | Oak National Academy

Which picture shows an insoluble substance?

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Answer explanation

This image shows an insoluble substance (here, sand) because it has not dissolved into the other substance (water). If a substance does not dissolve, it is described as insoluble.

Mass is measured in ...

• centimetres.

• millilitres.

• grams.

• centimetres-cubed.

Answer explanation

The standard unit for measuring mass in science is grams; however, it can also be measured in other units, like kilograms or tonnes.

Sugar dissolves in water, so sugar can be described as a ___ solid.

Answer explanation

Sugar and salt are described as soluble in water because they mix into the water and can no longer be seen with the naked eye.

A ___ is a material formed from two or more substances which can be physically separated.

Answer explanation

Mixtures are found all around us. For instance, sea water can be physically separated into water and salt.

Some students have been asked to describe this diagram using key terms. Who has used their key words correctly?

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Answer explanation

Izzy is correct that this is a pure solid. It is pure because all of the particles are the same. It is a solid because the particles are all touching and arranged in a regular pattern.

Melting is a reversible, physical change. Which of the following statements is also true about melting?

• Melting is what happens when a substance disappears.

• Melting occurs when solid particles become more regularly arranged.

• Melting is the process of a substance disappearing in a liquid.

• Melting occurs when solid particles become more irregularly arranged.

Answer explanation

Melting is a process by which a solid substance changes into a liquid. The particles in a liquid are irregularly arranged.