1.简单
What is radioactivity?
- AThe release of radiation by unstable atomic nuclei
- BThe flow of electrons through a metal wire
- CThe release of heat and light when fuels burn in air
- DThe glow produced by any hot object
2.简单
元素的原子序数告诉你什么?
- A原子核中质子和中子的总数
- B1 摩尔该元素中的原子数
- C每个原子中的质子数
- D每个原子中的中子数
3.简单
What are the units of molarity?
- AGrams of solute per litre of solution (g/L)
- BGrams of solute per 100 g of solution
- CMoles of solute per kilogram of the solvent used
- DMoles of solute per litre of solution (mol/L)
4.中等
In 2KClO₃ → 2KCl + 3O₂, how many moles of O₂ form from 4 mol of KClO₃?
- A3 mol
- B8 mol
- C6 mol
- D4 mol
5.中等
What is the mass of 0.5 mol of NaCl (molar mass 58.5 g/mol)?
- A117 g
- B58.5 g
- C29.25 g
- D0.5 g
6.中等
For the gas reaction N₂ + 3H₂ ⇌ 2NH₃, what is the effect of increasing the pressure?
- AThe equilibrium shifts to the left, toward N₂ and H₂
- BThe NH₃ breaks down completely
- CThere is no effect on the equilibrium
- DThe equilibrium shifts to the right, toward NH₃
7.困难
The true volume in a flask is 10.0 mL. A student measures it three times and gets 8.1 mL, 8.1 mL and 8.2 mL. How are these results best described?
- APrecise but not accurate
- BAccurate but not precise
- CBoth accurate and precise
- DNeither accurate nor precise
8.困难
Why does a burn from steam at 100 °C usually cause more damage than one from liquid water at 100 °C?
- ASteam particles are hotter than water particles at the same reading
- BSteam carries dissolved acid that damages the skin
- CSteam releases a large amount of extra energy as it condenses on the skin
- DLiquid water cannot pass any of its heat to the skin
答案
- 1. A · The release of radiation by unstable atomic nuclei
- 2. C · 每个原子中的质子数
- 3. D · Moles of solute per litre of solution (mol/L)
- 4. C · 6 mol
- 5. C · 29.25 g
- 6. D · The equilibrium shifts to the right, toward NH₃
- 7. A · Precise but not accurate
- 8. C · Steam releases a large amount of extra energy as it condenses on the skin
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