Year 9 Revision 1

Which of the following describes the density of a material?

• the amount of matter in the material

• the mass per unit volume of the material

• the pull of gravity on the material

• the volume per unit mass of the material

Answer explanation

Refer to formula of density. Density = Mass / Volume

Forces are applied to a beam pivoted at its centre.

Which example demonstrates the Principle of Moments?

• 
• 
• 
• 

Answer explanation

Principle of moments means when a body is balanced, total clockwise moment is equal to total anticlockwise moment

What is the nucleon number (mass number) of a nuclide?

• the number of neutrons

• the number of protons

• the number of neutrons and protons

• the number of protons and electrons

Answer explanation

Nucleon number (Mass number) is the total number of proton and neutron in a nucleus of an atom.

A mixture of two sugars was compared with four different sugars using chromotography.

The results are shown in the diagram.

Which two sugars does this mixture contain?

• 1 and 2

• 1 and 4

• 2 and 3

• 2 and 4

Answer explanation

Choose the spot of colours in sugars which travels the same distance as the spot of colours in the mixture as shown in the diagram.

The graph shows how the speed of a car changes over a period of time.

Which of the following is true?

• at P the car is at rest

• at Q the car has a non uniform acceleration

• at Q the car has uniform acceleration

• at R the car is accelerating

Answer explanation

At P, the car is at constant speed.

[Because the speed is the same]

At Q, the car is at constant acceleration.

[Because the speed is increasing]

At R, the car is at constant speed.

The beakers shown contain three different liquids.

Which statement about the densities of the liquids is correct?

• Liquid 1 has twice the density of liquid 3.

• Liquid 3 has twice the density of liquid 2.

• The liquids all have different densities.

• The liquids all have the same densities.

Answer explanation

Use the formula of density, D = M / V to choose the answer. Compare the density for each liquid as shown in the diagram.

Which of these objects will experience an elastic deformation?

• a car damaged in a collision

• a football being kicked

• a log hit by an axe

• a target hit by an arrow

Answer explanation

The ability of a material to stretch or extend and then return to it's original shape after force is removed is called elastic deformation.

Ionic compounds have high melting points because

• the ions are held together by strong electrostatic forces.

• the ions have inert gas structures.

• the electrons are attracted to the cations.

• metals transfer electrons to non-metals.

Answer explanation

An ionic compound is a giant structure of ions. Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions. These compounds have high melting points and high boiling points because of the large amounts of energy needed to break the many strong bonds as shown in the diagram.

What is always produced during photosynthesis?

• carbon dioxide

• methane

• oxygen

• water vapour

Answer explanation

Refer to definition or equations of photosynthesis as shown in the diagram.

The diagram shows a cell from the epidermis of an onion.

Which part allows some, but not all, dissolved substances to pass into or out of the cell?

• A

• B

• C

• D

Answer explanation

Allows some, but not all, dissolved substances to pass into or out of the cell. This is function of cell membrane.