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Class 10 Chemistry Chapter 23 Test 2 PDF | Monohydroxy Alkanes or Alcohols | Punjab Board 2027
Grade 10 Chemistry Chapter 23 Monohydroxy Alkanes or Alcohols Test 2
Prepare for your Class 10 Chemistry Chapter 23: Monohydroxy Alkanes or Alcohols examination with our Punjab Board 2027 Model Papers. This chapter-wise test series includes Class Test 2 and a Full Unit Test with Exercise, designed according to the new Chemistry syllabus issued by PECTAA Punjab. These Class 10 Chemistry test papers help students revise important concepts, practise textbook exercises, and prepare effectively for Punjab Board examinations. Use these free study resources to strengthen your preparation for the 2027 board exams.
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1.Fermentation must be carried out in the absence of:(Q-3)
(a) water(b) oxygen(c) Heat(d) Sugar
Answer: (b) oxygen – fermentation is anaerobic; in air the ethanol is oxidised to ethanoic acid.
2.Example of fermentation is:(Q-5)
(a) Rusting of iron(b) Preparation of Yogurt(c) Electrolysis of water(d) Burning of Fuel
Answer: (b) Preparation of Yogurt – bacteria (enzymes) convert milk sugar into lactic acid.
3.Ethanol concentration in the fermentation mixture usually does not exceed:(Q-7)
(a) 10 %(b) 12 %(c) 14 %(d) 15 %
Answer: (c) 14 % – above this the yeast is killed (please verify with your textbook key).
4.Alcohols burn in air to produce:(Q-12)
(a) CO & H2(b) C & H2O(c) CO2 & H2(d) CO2 & H2O
Answer: (d) CO2 & H2O – C2H5OH + 3O2 → 2CO2 + 3H2O
5.Burning of coal does not produce.(Q-16)
a) CO2(b) water vapourc) Heatd) Oxides of Sulphur
Answer: (b) water vapour – coal is almost pure carbon, so it gives CO2, heat and sulphur oxides (please verify with your textbook key).
6.Ethanol evaporates quickly due to its:(Q-21)
a) Densityb) Volatilityc) Colord) Taste
Answer: b) Volatility
7.Ethyl alcohol is an essential part of a first aid kit because it is:(Q-24)
a) Analgesicb) Antisepticc) Burningd) Drinking
Answer: b) Antiseptic – it kills germs on skin and wounds.
8.A major social risk associated with alcohol consumption is:(Q-26)
a) Better judgmentb) Improved healthc) Accidents & risky behaviord) Increased strength
Answer: c) Accidents & risky behavior
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Attempt any 7 Questions.7×2=14
i.What is fermentation? Give example.(Q-2)
Fermentation is the slow decomposition of complex organic compounds (sugar, starch) into simpler ones by the enzymes of micro-organisms such as yeast, giving ethanol and carbon dioxide. Example: glucose → ethanol + CO2 (also the souring of milk into yogurt).
ii.Write the conditions of Fermentation Process.(Q-4)
- Presence of yeast (enzymes invertase and zymase).
- Temperature of about 35°C.
- Absence of air (oxygen).
- Dilute sugar solution (such as molasses) with nutrients, kept for several days.
iii.Write any two comparison of hydration of ethane and fermentation process?(Q-7)
| Fermentation | Hydration of ethene |
|---|---|
| Slow process, takes days. | Fast, continuous process. |
| Raw material is renewable (sugar / starch). | Raw material is ethene from petroleum (non-renewable). |
iv.What happen when alcohols burn in air? Give example.(Q-9)
Alcohols burn in air with a pale blue, clean flame giving carbon dioxide, water and heat energy.
C2H5OH + 3O2 → 2CO2 + 3H2O + heat
C2H5OH + 3O2 → 2CO2 + 3H2O + heat
v.Why is more alcohol fuel needed to travel the same distance?(Q-14)
Alcohol molecules already contain oxygen (they are partly oxidised), so alcohol gives less heat per gram than petrol. Its energy content is lower, so a larger quantity of fuel is needed for the same distance.
vi.Write two disadvantages of alcohol used as fuels.(Q-13)
- Lower energy content, so more fuel is needed.
- Growing crops for fuel competes with food and land use.
- Absorbs water and can corrode engine parts.
vii.From where are alcohols produced?(Q-15)
By fermentation of sugars and starch (sugarcane molasses, grains, fruits) and by hydration of ethene obtained from petroleum.
viii.Does burning alcohol fuels increase atmospheric CO2(Q-17)
Burning releases CO2, but the plants used to make the alcohol absorbed the same amount by photosynthesis. So there is no net increase; alcohol fuels are nearly carbon neutral.
ix.Why alcohol can use in cosmetic industry?(Q-19)
Ethanol is a good solvent for fragrances and other ingredients, evaporates quickly leaving a cooling effect, and acts as an antiseptic and preservative.
x.Write the uses of methylated spirit.(Q-22)
Methylated spirit (ethanol denatured with methanol, poisonous) is used as a solvent for paints, varnishes and polishes, as fuel for spirit lamps and stoves, for cleaning glass and surfaces, and as an external antiseptic. It is not fit for drinking.
xi.Write the harmful effects of drinking ethyl alcohol.(Q-24)
- Damages the liver, brain, heart and stomach.
- Causes addiction and loss of judgment and self-control.
- Leads to accidents, risky behaviour and social problems.
- Large amounts can cause coma and death.
SECTION-II
1.How do the properties of ethyl alcohol help us to utilize it as a fuel?(Ex. C. 23.3)
- Burns cleanly with a pale flame, giving only CO2 and water (less pollution).
- High heat of combustion (about 1367 kJ/mol).
- Volatile liquid that easily mixes with air, so it burns efficiently.
- Mixes with petrol in any ratio (gasohol); easy to store and transport.
- Renewable: produced by fermentation of plant material.
2.Describe the preparation of ethanol by fermentation process.(Ex. D. 23.2)
A dilute solution of sugar (molasses) is mixed with yeast and kept at about 35°C, away from air, for several days.
Invertase converts sucrose to glucose and fructose:
C12H22O11 + H2O → C6H12O6 + C6H12O6
Zymase then converts glucose to ethanol:
C6H12O6 → 2C2H5OH + 2CO2
When the ethanol reaches about 14%, the yeast stops working. The ethanol is then separated by fractional distillation (about 95% pure, rectified spirit).
Invertase converts sucrose to glucose and fructose:
C12H22O11 + H2O → C6H12O6 + C6H12O6
Zymase then converts glucose to ethanol:
C6H12O6 → 2C2H5OH + 2CO2
When the ethanol reaches about 14%, the yeast stops working. The ethanol is then separated by fractional distillation (about 95% pure, rectified spirit).
