Elements, compounds and mixtures: Practice Questions

Which of the following is a characteristic of a pure compound but not a mixture?

A substance X has a fixed melting point and can be decomposed into two simpler substances by heating. The simpler substances produced cannot be broken down further by chemical means.

Based on this information, what is substance X?

The diagram shows the arrangement of atoms in an alloy. Large atoms of metal X form a lattice with smaller atoms of element Y dispersed between them.
Why is this alloy typically harder and stronger than the pure metal X?

Which row correctly classifies the substances diamond, carbon dioxide, and air?

Which observation provides evidence that a solid sample is a mixture of iron filings and sulfur, rather than the compound iron(II) sulfide?
1. The sulfur can be dissolved by a liquid solvent while the iron remains.
2. The iron can be removed from the sample using a magnet.
3. The sample has the same chemical properties as both iron and sulfur.

Methane has the chemical formula \(CH_{4}\). State whether methane is an element or a compound and give one reason for your answer based on its composition.

Explain how the melting point of a sample can be used to distinguish between a pure substance and a mixture.

Differentiate between an element, a compound, and a mixture by stating one key characteristic for each. Give one example of each.