Recap: LSS Chemistry

Air is a/an

• element

• compound

• mixture

Answer explanation

Air is a mixture consisting of nitrogen, oxygen, carbon dioxide, water vapour and other gases.

The Periodic Table consists of

• elements

• compounds

• mixtures

Answer explanation

The periodic table consists of elements, which can also be classified as metals and non-metals.

Match the following set-ups to the separation techniques.

• Evaporation

• 
• Paper Chromatography

• 
• Filtration

• 
• Distillation

• 

Answer explanation

The diagram shows an overview of the different separation techniques and their set-ups.

Match the following arrangement of particles to the state of matter that they represent.

• Liquid

• 
• Gas

• 
• Solid

• 

Answer explanation

From a solid --> liquid --> gas, the particles are spaced further apart and in a more disorderly manner.

Melting is the process in which a ​ (a)   changes into a ​ (b)   , ​ (c)   a change in temperature.

• solid
• liquid
• without
• gas
• with

Answer explanation

When a solid is heated, its particles gain energy. They vibrate faster about their fixed positions. They eventually gain enough energy to overcome the very strong forces of attraction between them. The solid

melts and becomes a liquid. There is no change in temperature during the melting process.

Fluorine has ___ protons.

Answer explanation

Which of the following are molecules?

• He

• Cl

Answer explanation

An atom can combine with one or more atoms of the same element or different elements to form molecules. A molecule is made up of two or

more atoms that are chemically combined.

Match the following sub-atomic particles to their charges.

• -1

• Electron

• 0

• Proton

• +1

• Neutron

Answer explanation

An acid reacts with a metal to form a salt and ​ (a)   . ​

• hydrogen gas
• carbon dioxide gas
• water

An acid reacts with an alkali to form a salt and ​ (a)   . This reaction is also known as a/an​ (b)   reaction. ​

• water
• neutralisation
• carbon dioxide gas
• hydrogen gas
• combustion
• thermal decomposition
• oxidation