Question 1
A student finds a shiny object and tests it with a bar magnet. The object is not attracted. Which conclusion is correct?No clue? Show me the answer
Correct answerCorrect!
IncorrectStep-by-step walkthrough
Choose a solution method
Method #1Direct ApproachStep 1: Identify the key concept
The question tests whether students know that not all metals are magnetic. Only iron, steel, cobalt, and nickel are strongly magnetic.
Step 2: Apply the rule about magnetic metals
Metals such as aluminium and copper are real metals — they are shiny and conduct electricity — but they are not attracted to magnets. A shiny, non-magnetic object could easily be one of these metals.
Step 3: Rule out incorrect reasoning
It is a common mistake to assume all metals are magnetic. The fact that an object is not attracted to a magnet tells us nothing about whether it is a metal or a non-metal on its own.
Step 4: Select the correct answer
The correct conclusion is that the object could be a metal like aluminium or copper, since these metals are non-magnetic. We cannot rule out that it is a metal just because the magnet had no effect.
Method #2Process of EliminationStep 1: Identify what is being asked
We need to find the correct conclusion when a shiny, non-magnetic object is tested with a magnet.
Step 2: Eliminate 'cannot be a metal'
"The object cannot be a metal because metals are always magnetic" is false — aluminium, copper, zinc, and gold are all metals that are not magnetic. This option is eliminated.
Step 3: Eliminate 'must be plastic'
"Must be made of plastic" is too strong a conclusion. Many non-magnetic materials exist, including non-magnetic metals. We cannot conclude it must be plastic.
Step 4: Eliminate 'must be ceramic'
"Must be ceramic" is also incorrect. Ceramics are usually not shiny in the same way as metals, and we have no basis to conclude it must be ceramic.
Step 5: Select the correct answer
The remaining option — "could be a metal like aluminium or copper" — is correct. It correctly acknowledges that some metals are non-magnetic.
Question 2
Which of the following lists contains ONLY magnetic materials?No clue? Show me the answer
Correct answerCorrect!IncorrectStep-by-step walkthrough
Choose a solution method
Method #1Direct ApproachStep 1: Recall the magnetic metals
The strongly magnetic (ferromagnetic) metals are iron, steel, cobalt, and nickel. All other metals — including aluminium, copper, and zinc — are not magnetic.
Step 2: Check each list
We need a list where every material is magnetic. Check: iron ✓, steel ✓, cobalt ✓. This list contains only magnetic materials.
Step 3: Confirm the answer
Iron, steel, cobalt is the correct answer because all three are ferromagnetic materials that are strongly attracted to a magnet.
Method #2Process of EliminationStep 1: Identify what is being asked
We need the list where every material listed is magnetic. Any list containing a non-magnetic material is wrong.
Step 2: Eliminate lists containing aluminium
"Iron, aluminium, nickel" includes aluminium, which is a non-magnetic metal. This list is eliminated.
Step 3: Eliminate lists containing copper
"Copper, steel, cobalt" includes copper, which is not magnetic. This list is eliminated.
Step 4: Eliminate lists containing zinc
"Steel, zinc, iron" includes zinc, which is not magnetic. This list is eliminated.
Step 5: Select the correct answer
Iron, steel, cobalt is the only list where all three materials are strongly magnetic, making it the correct answer.
14 more questions in this topic
Pick this up in your Library: it holds the whole topic, notes, cheatsheet and questions. Your answers here are kept on this device.