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Class 10 Chemistry Chapter 23 Monohydroxy Alkanes or Alcohols Test 8 PDF | Punjab Board 2027 Model Papers
Grade 10 Chemistry Chapter 23 Test No.8
Prepare for your Class 10 Chemistry Chapter 23: Monohydroxy Alkanes or Alcohols examination with our Chapter Test 8, Full Unit Test, and Chapter-Wise Test Series. These Class 10 Chemistry Test Papers for Punjab Board 2027 are designed according to the new syllabus issued by PECTAA Punjab. Students can use these chapter-wise tests and full-unit assessments to revise important concepts, practise exam-style questions, and improve their preparation for the 2027 board examinations. Explore the Punjab Board 2027 Model Papers for effective Chemistry exam preparation.
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PAPER NO.08
CHEMISTRY
CHAPTER
WISE
WISE
Roll No.(in Figures): (in Words):
ABCD
1ABCD
2ABCD
3ABCD
4ABCD
ABCD
5ABCD
6ABCD
7ABCD
8ABCD
ABCD
9ABCD
10ABCD
11ABCD
12ABCD
NOTE:Four possible answers A, B, C and D to each question are given. The choice which you think is correct, fill that circle in front of that question with Marker or Pen ink. Cutting or filling two or more circles will result in zero mark in that question.
Q1.12
1.Which conditions are considered best for the fermentation of glucose?
- (A) 35 °C, fresh yeast, absence of oxygen
- (B) 45 °C, yeast
- (C) 45 °C, absence of oxygen
- (D) 35 °C, fresh yeast
2.The enzyme in yeast acts as:
- (A) Reactant
- (B) Product
- (C) Catalyst
- (D) Solvent
3.Which catalyst other than H3PO4 can also be used for hydration of alkenes?
- (A) NaOH
- (B) H2SO4
- (C) CH3COOH
- (D) Ni
4.When alcohols burn in air they produce:
- (A) CO and H2
- (B) CO2 and H2O
- (C) CO2 and H2
- (D) CO and H2O
5.The most environment friendly fuel is:
- (A) coal
- (B) kerosene oil
- (C) ethanol
- (D) wood
6.Which alcohol Contain four carbon atom?
- (A) Methanol
- (B) Ethanol
- (C) Propanol
- (D) Butanol
7.Which property or properties of ethanol make it suitable to be used in cosmetic industry?
- (A) Easily Flammable
- (B) Highly volatile and deodorizing
- (C) Antipyretic
- (D) Sedative
8.Ethanol reduces greenhouse gas emissions by what percentage compared to petrol?
- (A) 20-30%
- (B) 44-52%
- (C) 60-70%
- (D) 80-90%
9.Which property of ethanol makes it suitable for cleaning wounds?
- (A) Good solvent
- (B) Volatility
- (C) Antiseptic
- (D) Deodorizing
10.Ethanol is an important part of cosmetic industry because it is:
- (A) Highly viscous
- (B) Non-volatile
- (C) Highly volatile
- (D) Insoluble in water
11.Which alcohol is used to accomplish all the following tasks:
It is added in petrol to improve combustion. It serves as a feed stock to prepare vinegar and many other organic compounds.
- (A) Propanol
- (B) Propan-2-ol
- (C) Ethanol
- (D) Methanol
12.Alcohol which has the maximum heat of combustion is:
- (A) CH3CH2CH2OH
- (B) CH3CH2OH
- (C) CH3OH
- (D) CH3CH2CH2CH2OH
Here is Subjective Part of Paper.
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Roll No.(in Figures): (in Words):
Q2.Write short answers to any FIVE (5) questions:(5×2=10)
- (i)Give two advantages of burning of alcohols over the burning of fossil fuel?Alcohols burn cleanly to CO2 and H2O with little smoke, soot, CO or sulphur oxides, and they are renewable (made from sugar crops), while fossil fuels are not.
- (ii)What are monohydroxy alkanes or alcohols?Organic compounds obtained by replacing one hydrogen of an alkane with one –OH group. General formula: CnH2n+1OH.
- (iii)Which properties of ethyl alcohol make it useful for cosmetic industry?It is highly volatile, a good solvent, deodorizing and antiseptic.
- (iv)What is the role of yeast in fermentation reaction?Yeast supplies enzymes (zymase, invertase) that act as catalysts to convert sugar into ethanol and CO2.
- (v)Why does fermentation stop when ethanol concentration reaches 15%?At about 15% ethanol the yeast enzymes are poisoned and destroyed, so the reaction cannot continue.
- (vi)How is ethyl alcohol important for pharmaceutical industry?It is used as a solvent for medicines (tinctures, syrups), as an antiseptic/disinfectant and as a preservative.
- (vii)Which method for preparation of ethanol involves renewable source?Fermentation of sugars (from sugarcane, molasses, starch crops) with yeast.
- (viii)What are the advantages of fermentation over hydration of ethene?It uses renewable raw materials, works at low temperature and pressure, needs simple apparatus and is cheaper and eco-friendly.
Q3.Write short answers to any FIVE (5) questions:(5×2=10)
- (i)Give any two disadvantages of fermentation reactions.It is a slow process, and the ethanol is impure and dilute (max. about 15%), so it needs distillation.
- (ii)Why does butanol evolve a higher amount of heat than propanol when burnt in oxygen?Butanol (C4H9OH) has more carbon and hydrogen atoms, so more bonds form (more CO2 and H2O) and more heat is released per mole.
- (iii)Which bonds break and which bonds form during combustion of alcohols?C–H, C–C, C–O, O–H bonds of the alcohol and O=O bonds of oxygen break; C=O bonds (in CO2) and O–H bonds (in H2O) form.
- (iv)Write the conditions involved in the hydration of ethene.Ethene and steam, H3PO4 catalyst, about 300 °C and 60–70 atm pressure.
- (v)Is combustion of alcohols exothermic or endothermic?Exothermic – heat is given out.
- (vi)Why do alcohols burn completely in excess air?Plenty of oxygen converts all carbon to CO2 and all hydrogen to H2O, so no CO or soot is formed.
- (vii)How ethanol is obtained as a by-product in sugar industry?Molasses left after sugar crystallization still contains sugar; fermenting it with yeast gives ethanol.
- (viii)Write down the general formula of alcohols.CnH2n+1OH (or R–OH).
Q4.Write short answers to any FIVE (5) questions:(5×2=10)
- (i)How does ethanol reduce greenhouse gas emissions?It burns cleanly with less CO and hydrocarbons, and the CO2 released is taken back by the plants grown for the next crop. Compared with petrol, emissions fall by about 44–52%.
- (ii)Why do we get relatively impure alcohol in the fermentation process?The mixture contains water, unused sugar, yeast and by-products, so the ethanol obtained is dilute and impure.
- (iii)In which products of cosmetic ethanol is found?Perfumes, deodorants, aftershaves, hair sprays, lotions and creams.
- (iv)Write the impact of ethanol in daily life.Used as fuel and fuel additive, solvent, antiseptic, in medicines, cosmetics and in making vinegar and other organic compounds.
- (v)How do properties of ethyl alcohol help us to utilize it as fuel?It has a high heat of combustion, burns cleanly, is renewable and mixes with petrol to improve combustion.
- (vi)What is the role of ethanol in perfumes?It dissolves the fragrance oils and, being volatile, evaporates quickly and spreads the scent.
- (vii)What are the harmful effects of ethyl alcohol?In large amounts it is toxic: it damages the liver and brain, causes addiction, intoxication and accidents.
- (viii)What is methylated spirit?Ethanol made unfit for drinking by adding methanol (and a dye); it is used as fuel and solvent.
(PART - II)
Note: Attempt any TWO questions.(2 × 9 = 18)
Q5.(a)Give a comparison of fermentation reaction and catalytic hydration of ethene for the preparation of ethanol.5
| Point | Fermentation | Hydration of ethene |
|---|---|---|
| Raw material | Sugar / molasses (renewable) | Ethene from petroleum (non-renewable) |
| Catalyst | Yeast enzymes | H3PO4 |
| Conditions | About 35 °C, no oxygen | 300 °C, 60–70 atm |
| Speed | Slow, batch process | Fast, continuous |
| Product | Dilute, impure (max. 15%) | Pure ethanol |
(b)Describe the applications of ethanol in pharmaceutical and cosmetic industries?4
Pharmaceutical: solvent for syrups and tinctures, antiseptic for cleaning wounds, preservative. Cosmetic: solvent and carrier in perfumes, deodorants, lotions and hair sprays; volatile, so it dries quickly and leaves the fragrance.
Q6.(a)Discuss the preparation of ethanol by hydration of ethene or Ethylene.5
Ethene and steam are passed over H3PO4 (on silica) at about 300 °C and 60–70 atm.
CH2=CH2 + H2O ⇌ CH3CH2OH
The reaction is reversible, so unreacted ethene is recycled. Ethanol is condensed and purified. H2SO4 can also be used as catalyst.
CH2=CH2 + H2O ⇌ CH3CH2OH
The reaction is reversible, so unreacted ethene is recycled. Ethanol is condensed and purified. H2SO4 can also be used as catalyst.
(b)Explain combustion of Alcohols.4
Alcohols burn in excess air to give CO2, H2O and heat (exothermic).
C2H5OH + 3O2 → 2CO2 + 3H2O + heat
Bonds in the alcohol and oxygen break; C=O and O–H bonds form. Heat of combustion rises as the carbon chain gets longer.
C2H5OH + 3O2 → 2CO2 + 3H2O + heat
Bonds in the alcohol and oxygen break; C=O and O–H bonds form. Heat of combustion rises as the carbon chain gets longer.
Q7.(a)Describe applications of Alcohols as fuels.5
- Ethanol is blended with petrol (gasohol) to improve combustion.
- They burn cleanly with a smokeless flame and release much heat.
- Methanol and ethanol are used as fuel in spirit lamps and stoves, and in racing cars.
- Ethanol is renewable and reduces greenhouse gas emissions by about 44–52%.
(b)Explain the impact of alcohols on daily life.4
Alcohols are used as fuels, solvents, antiseptics, in medicines, perfumes and cosmetics, and to make vinegar and other organic compounds. Harmful side: methanol and excess ethanol are poisonous and cause addiction and liver damage.
