1.简单
What should a student always wear to protect the eyes when working with chemicals?
- AReading glasses
- BContact lenses
- CSafety goggles
- DSunglasses
2.简单
What is the name for the attraction of water molecules to each other?
- AAdhesion
- BDiffusion
- CCohesion
- DOsmosis
3.简单
How many electrons are shared in a double covalent bond?
- A6
- B4
- C8
- D2
4.中等
Water has a high specific heat capacity. How does this help the human body?
- AIt makes water a poor solvent for salts
- BIt helps keep body temperature stable
- CIt makes the blood more acidic
- DIt allows oxygen to dissolve in water more easily
5.中等
Which equation shows a combustion reaction?
- AZn + CuSO₄ → ZnSO₄ + Cu
- BCaCO₃ → CaO + CO₂
- CNaOH + HCl → NaCl + H₂O
- DC₂H₅OH + 3O₂ → 2CO₂ + 3H₂O
6.中等
What is the oxidation number of sulfur in H₂SO₄?
- A−2
- B+2
- C+4
- D+6
7.困难
Burning a match is strongly exothermic, so why does it not catch fire until it is struck?
- AStriking makes the reaction endothermic
- BStriking supplies the activation energy to start the reaction
- CStriking pushes extra oxygen into the chemicals of the match head
- DThe match must first absorb all its energy from the air
8.困难
Diamond is extremely hard and has a very high melting point. Which explanation is correct?
- AIt contains delocalised electrons like a metal
- BIt is made of separate small molecules with strong forces between them
- CEach carbon is covalently bonded to four others in a giant network
- DIt is held together by ionic bonds between C⁺ and C⁻ ions
答案
- 1. C · Safety goggles
- 2. C · Cohesion
- 3. B · 4
- 4. B · It helps keep body temperature stable
- 5. D · C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O
- 6. D · +6
- 7. B · Striking supplies the activation energy to start the reaction
- 8. C · Each carbon is covalently bonded to four others in a giant network
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