Tutopiya: Study Resources for IGCSE, IB, GCSE & A-Levels

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6 MCQs

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1
Which of the following is a compound?
Answer & explanation
Correct: option C
CO₂ contains two different elements (carbon and oxygen) chemically bonded — a compound. O₂ and Au are elements; iron + sulfur is a mixture.
2
How many oxygen atoms are in one unit of aluminium sulfate, Al₂(SO₄)₃?
Answer & explanation
Correct: option C
(SO₄)₃ means 3 × SO₄ = 3 × 4 = 12 oxygen atoms.
3
Which of these is a balanced symbol equation?
Answer & explanation
Correct: option B
2H₂ gives 4 H on the left; 2H₂O gives 4 H and 2 O on the right; O₂ gives 2 O on the left. All balanced.
4
Which of these is a physical change?
Answer & explanation
Correct: option C
Dissolving salt is physical — no new substance is made and you can recover the salt by evaporation. The other three form new substances.
5
What state symbol is used for a substance dissolved in water?
Answer & explanation
Correct: option D
(aq) stands for aqueous (from Latin 'aqua' = water) — meaning dissolved in water.
6
What is the chemical symbol for sodium?
Answer & explanation
Correct: option C
Sodium's symbol comes from the Latin natrium. The symbol S is sulfur.