Science Revision

How many atoms are there in one molecule of calcium carbonate, CaCO₃?

• 3

• 4

• 5

• 6

What does the diagram represent?

• atoms of element

• molecules of element

• molecules of compound

• mixture of elements

What does the diagram represent?

• atoms of element

• molecules of element

• molecules of compound

• mixture of compounds

What does the diagram represent?

• molecules of element

• molecules of compound

• mixture of elements

• mixture of element and compound

What is a molecule?

• smallest particle of an element

• two or more atoms chemically combined

Which current does the arrows on the diagram show?

• red: conventional current, blue: electron

• blue: conventional current, red: electron

What does this circuit symbol represent?

• fixed resistor

• variable resistor / rheostat

• fuse

What does this circuit symbol represent?

• fixed resistor

• variable resistor / rheostat

• fuse

Which of the following are precautions to prevent electrocution?

I. Electrical appliances or gadgets must not be used in wet places.

II. Call a certified electrician to repair damaged electrical appliances or cables.

III. Do not insert any item, such as a screwdriver, into an electrical socket.

• I and II only

• I and III only

• II and III only

• All of the above

The earth wire provides a path of _________________ for a large current to flow directly from the live wire to the ground or earth if there is a fault in an electrical appliance.

• low voltage

• high voltage

• low resistance

• high resistance