1.Dễ
Elements in the same period of the periodic table have the same number of what?
- AOccupied electron shells
- BNeutrons
- CProtons
- DValence electrons
2.Dễ
Which property is typical of bases?
- AThey feel slippery
- BThey taste sour
- CThey have a pH below 7
- DThey turn blue litmus red
3.Dễ
Which electrons take part in chemical bonding?
- AThe electrons closest to the nucleus
- BAll electrons take part equally
- CThe valence (outermost) electrons
- DOnly the electrons in the first shell
4.Trung bình
How many moles of gas are in 44,8 L at STP (0 °C and 1 atm)?
- A0,5 mol
- B22,4 mol
- C2 mol
- D44,8 mol
5.Trung bình
What is carbon-14 dating used for?
- AMeasuring body temperature
- BDetecting carbon monoxide in a room
- CEstimating the age of material that was once alive
- DFinding the exact age of rocks that are billions of years old
6.Trung bình
Sản phẩm của sự cháy hoàn toàn một hydrocarbon như methane là gì?
- AOxygen và nước
- BCarbon monoxide và hydrogen
- CCarbon dioxide và nước
- DCarbon và khí hydrogen
7.Khó
Each C=O bond in carbon dioxide is polar, yet the CO₂ molecule is nonpolar. Why?
- AThe bonds are ionic, not covalent
- BCarbon and oxygen have the same electronegativity
- CCarbon has lone pairs that cancel the dipoles
- DThe molecule is linear, so the two bond dipoles cancel out
8.Khó
Which phase change absorbs energy from the surroundings (is endothermic)?
- ASublimation
- BFreezing
- CCondensation
- DDeposition
Đáp án
- 1. A · Occupied electron shells
- 2. A · They feel slippery
- 3. C · The valence (outermost) electrons
- 4. C · 2 mol
- 5. C · Estimating the age of material that was once alive
- 6. C · Carbon dioxide và nước
- 7. D · The molecule is linear, so the two bond dipoles cancel out
- 8. A · Sublimation
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