Class 9 Chemistry · Chapter 4 · Test 10

Final Full Test

25 MCQs covering chemical formulas, empirical and molecular formulas, ionic compounds, structural formulas, Avogadro's number, mole concept, molar mass, balancing chemical equations, mole ratios, stoichiometric calculations, mass calculations, and percentage composition.

MCQs

25 questions · 20 min · 25 marks

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Sample questions

The first 5 of 25. Try each one, then tap to see the answer.

Question 1
Which formula represents a molecule of oxygen?
- AO
- BO2
- CO3
- D2O
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Answer: B
Oxygen normally exists as a diatomic molecule with formula O2.
Question 2
Which formula represents sodium chloride?
- ANaCl
- BNa2Cl
- CNaCl2
- DNa2Cl2
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Answer: A
Sodium forms Na+ and chlorine forms Cl- so their ratio is 1:1 giving NaCl.
Question 3
What is the empirical formula of hydrogen peroxide H2O2?
- AH2O2
- BHO
- CH2O
- DO2
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Answer: B
The empirical formula is the simplest whole number ratio of atoms so H2O2 becomes HO.
Question 4
What is the molecular formula if the empirical formula is CH2 and the molecular mass is 28?
- ACH2
- BC2H4
- CC3H6
- DC4H8
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Answer: B
The empirical formula mass is 14 and 28 divided by 14 is 2 so the molecular formula is C2H4.
Question 5
What is the formula of magnesium chloride?
- AMgCl
- BMgCl2
- CMg2Cl
- DMg2Cl2
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Answer: B
Magnesium forms Mg2+ and chloride forms Cl- so two chloride ions are needed for one magnesium ion.

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