1.Easy
What does the octet rule state?
- AAtoms tend to gain, lose or share electrons to get 8 outer electrons
- BEvery stable atom has exactly 8 protons in its nucleus
- CAn atom can form a maximum of 8 covalent bonds
- DEvery stable molecule contains exactly 8 atoms
2.Easy
What is the SI unit of energy?
- ANewton
- BKelvin
- CJoule
- DWatt
3.Easy
What are the usual units of molar mass?
- Ag/mol
- Bg/L
- Cmol/L
- Dmol/g
4.Medium
Which substance is oxidised in the reaction 2Mg + O₂ → 2MgO?
- AMagnesium, because it gains electrons
- BOxygen, because it loses electrons
- CMagnesium, because it loses electrons
- DNeither substance changes its charge
5.Medium
Which property is typical of ionic compounds such as NaCl?
- ABeing soft and easily bent like metals
- BConducting electricity as dry solids
- CLow melting points and being gases at room temperature
- DHigh melting points; they conduct when dissolved
6.Medium
0.5 mol of KCl is dissolved to make 250 mL of solution. What is its molarity?
- A0.5 M
- B125 M
- C0.125 M
- D2 M
7.Hard
In the reaction NH₃ + H₂O ⇌ NH₄⁺ + OH⁻, which substance acts as the Brønsted–Lowry acid?
- AH₂O
- BNH₃
- CNH₄⁺ only
- DOH⁻
8.Hard
Which list puts fluorine, chlorine and bromine in order of increasing electronegativity?
- ACl < Br < F
- BF < Cl < Br
- CBr < F < Cl
- DBr < Cl < F
Answer key
- 1. A · Atoms tend to gain, lose or share electrons to get 8 outer electrons
- 2. C · Joule
- 3. A · g/mol
- 4. C · Magnesium, because it loses electrons
- 5. D · High melting points; they conduct when dissolved
- 6. D · 2 M
- 7. A · H₂O
- 8. D · Br < Cl < F
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