Elements, Compounds and Mixtures

Which list contains an element, a compound and a mixture?

• Air, copper, soil

• air, pure water, sodium chloride

• copper, soil, pure water

• tap water, soil, sodium chloride

Substances can be broadly classified into three categories, which are elements, compounds and mixtures. Which of the following statement is correct?

• Elements contain different atoms.

• Compounds consists of elements that are not chemically combined.

• Mixtures consist of elements that are chemically combined.

• A mixture can contain elements and compounds.

The smallest particles of an element that have the chemical properties of that element.

• monoatomic element

• diatomic element

• atoms

• ions

What is the total number of atoms present in one unit of chromium(III) sulfate, Cr₂(SO₄)₃?

• 3

• 7

• 15

• 17

which of the following describes a mixture?

• its components can be separated by physical means

• its components is fixed

• the properties of its components are different from that of the mixture

• two or more substances are chemically combined

Two elements R and S combine to form the compound RS2. Which of the following statements are true?

• An energy change occurs when RS₂ is formed

• RS₂ will have a colour in between those of R and S.

• RS₂ will have the properties of both R and S.

• The ratio of R : S atom is 2:1

When a green solid X is heated, it forms a black solid and a gas. Therefore, X ....

• does not contain a metal

• is a compound made up of at least two elements

• is a mixture of two elements

• must be a mixture because it can be separated into two substances.