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Science M.C.Q

Carbon and its Compounds · CBSE STD 10 (CBSE - English Medium). 193 questions.

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M.C.Q

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MCQ 21 Mark
In the neighbourhood of your school, hard water required for an experiment is not available. Select from the following groups of salts available in your school, a group each member of which, if dissolved in distilled water, will make it hard :
  • A
    Sodium chloride, calcium chloride.
  • B
    Potassium chloride, sodium chloride.
  • C
    Sodium chloride, magnesium chloride.
  • ✓
    Calcium chloride, magnesium chloride.
Answer
Correct option: D.
Calcium chloride, magnesium chloride.
Hardness of water is due to the calcium and magnesium ions.
So to make water hard salt of calcium chloride and magnesium chloride is added to distilled water.
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MCQ 31 Mark
In a locality, hard water, required for an experiment, is not available. However, the following salts are available in the school laboratory:
  1. Sodium sulphate.
  2. Calcium sulphate.
  3. Magnesium chloride.
  4. Sodium chlorid.
  5. Calcium chloride.
  6. Potassium sulphate.
Which of the above salts may be dissolved in water to obtain hard water for the experiment?
  • ✓
    $2, 3$ and $5$
  • B
    $1, 2$ and $5$
  • C
    $1, 2, 4$ and $6$
  • D
    $3$ and $5$ only
Answer
Correct option: A.
$2, 3$ and $5$
Hard water contains $\mathrm{Ca}^{2+}$ and $\mathrm{Mg}^{2+}$ ions.
So, the salts that can be added to water to make it hard are calcium sulphate, calcium chloride and magnesium chloride.
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MCQ 41 Mark
In an experiment to study the properties of ethanoic acid, a student takes about $3 mL$ of ethanoic acid in a dry test tube. He adds an equal amount of distilled water to it and shakes the test tube well. After some time he is likely to observe that.
  • A
    A colloid is formed in the test tube.
  • ✓
    The ethanoic acid dissolves readily in water.
  • C
    The solution becomes light orange.
  • D
    Water floats over the surface of ethanoic acid.
Answer
Correct option: B.
The ethanoic acid dissolves readily in water.
On addition of $3ml$ of ethanoic acid to a test tube containing $3ml$ of distilled water, a clear solution will be formed having no color due to high Solubility of ethanoic acid in water.
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MCQ 51 Mark
While studying the saponification reaction, what do you observe when you mix an equal amount of colourless vegetable oil and $20\%$ aqueous solution of $\ce{NaOH}$ in a beaker?
  • A
    The colour of the mixture has become dark brown.
  • B
    A brisk effervescence is taking place in the beaker.
  • ✓
    The outer surface of the beaker has become hot.
  • D
    The outer surface of the beaker has become cold.
Answer
Correct option: C.
The outer surface of the beaker has become hot.
While studying saponification reaction when equal amount of colorless vegetable oil and $20\%$ aqueous solution of $\ce{NaOH}$ in mixed in a beaker, the beaker becomes hot from outside.
This is because, $\ce{NaOH}$ reacts with the aqueous solution to release heat and an exothermic reaction takes place.
Hence option c is correct.
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MCQ 61 Mark
For preparing soap in the laboratory we require an oil and a base. Which of the following combinations of an oil and a base would be best suited for the preparation of soap?
  • A
    Castor oil and calcium hydroxide.
  • B
    Turpentine oil and sodium hydroxide.
  • ✓
    Castor oil and sodium hydroxide.
  • D
    Mustard oil and calcium hydroxide.
Answer
Correct option: C.
Castor oil and sodium hydroxide.
Castor in soaps contributes to fluffy, stable lather, conditioning, moisturizing, quicker trace, softer soap. Turpentine is for medicinal and mustard oil is used for cooking.
Sodium hydroxide is a strong base soluble in water. However, calcium is not preferred as it forms scum. Hence, castor oil and sodium hydroxide are best suited for soap.
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MCQ 71 Mark
What do we observe on pouring acetic acid on red and blue litmus papers?
  • ✓
    Red litmus remains red and blue litmus turns red.
  • B
    Red litmus turns blue and blue litmus remains blue.
  • C
    Red litmus turns blue and blue litmus turns red.
  • D
    Red litmus becomes colourless and blue litmus remains blue.
Answer
Correct option: A.
Red litmus remains red and blue litmus turns red.
That is red litmus remains red and blue litmus turns red.
This is because acetic acid is an acid that is mainly used in vinegar and acids always turn blue litmus red.
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MCQ 81 Mark
While preparing soap a small quantity of common salt is generally added to the reaction mixture of vegetable oil and sodium hydroxide. Which one of the following may be the purpose of adding common salt?
  • A
    To reduce the basic nature of the soap.
  • B
    To make the soap neutral.
  • C
    To enhance the cleansing power of the soap.
  • ✓
    To favour the precipitation of the soap.
Answer
Correct option: D.
To favour the precipitation of the soap.
Soap is sodium or potassium salt of fatty acids, and these salts are less soluble than a strong electrolyte sodium chloride.
So, sodium chloride is added to precipitate the soap by common-ion effect.
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MCQ 91 Mark
While studying saponification reaction, a student measures the temperature of the reaction mixture and also finds its nature using blue/red litmus paper. On the basis of his observations the correct conclusion would be :
  • A
    The reaction is exothermic and the reaction mixture is acidic.
  • B
    The reaction is endothermic and the reaction mixture is acidic.
  • C
    The reaction is endothermic and the reaction mixture is basic.
  • ✓
    The reaction is exothermic and the reaction mixture is basic.
Answer
Correct option: D.
The reaction is exothermic and the reaction mixture is basic.
It’s an endothermic reaction meaning it absorbs surrounding heat. Formation of soap that is saponification involves base $($usually sodium hydroxide, $\ce{NaOH)}$ hydrolysis of triglycerides, which are esters of fatty acids, to form the sodium salt of a carboxylate. Hence reaction mixture is basic.
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MCQ 101 Mark
We need $20\%$ aqueous solution of sodium hydroxide for the study of saponification reaction. When we open the lid of the bottle containing solid sodium hydroxide we observe it in which form?
  • A
    Colourless transparent beads.
  • B
    Small white beads.
  • ✓
    White pellets/ flakes.
  • D
    Fine white powder.
Answer
Correct option: C.
White pellets/ flakes.
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MCQ 111 Mark
A student puts a drop of reaction mixture of a personification reaction first on a blue litmus paper and then on a red litmus paper. He may observe that:
  • A
    There is no change in the blue litmus paper and the red litmus paper turns white.
  • B
    There is no change in the red litmus paper and the blue litmus paper turns red.
  • ✓
    There is no change in the blue litmus paper and the red litmus paper turns blue.
  • D
    No change in colour is observed in both the litmus papers.
Answer
Correct option: C.
There is no change in the blue litmus paper and the red litmus paper turns blue.
Saponification reaction mixture is basic in nature. Formation of soap that is saponification involves base $($usually sodium hydroxide $, \ce{NaOH)}$ hydrolysis of triglycerides, which are esters of fatty acids, to form the sodium salt of a carboxylate. Hence reaction mixture is basic.
So, the student will observe that there is no change in the blue litmus paper but red litmus will turn blue.
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MCQ 121 Mark
A student takes about $4 mL$ of distilled water in four test tubes marked $P, Q, R$ and $S$. He then dissolves in each test tube an equal amount of one salt in one test tube, namely sodium sulphate in $P,$ potassium sulphate in $Q,$ calcium sulphate in $R$ and magnesium sulphate in $S$. After that he adds an equal amount of soap solution in each test tube. On shaking each of these test tubes well, he observes a good amount of lather $($foam$)$ in the test tubes marked.
  • ✓
    $P$ and $Q$.
  • B
    $Q$ and $R.$
  • C
    $P, Q$ and $S.$
  • D
    $P, R$ and $S.$
Answer
Correct option: A.
$P$ and $Q$.
Soap molecules are sodium or potassium salts of long $-$ chain carboxylic acids. On reaction with calcium or magnesium ions, the soap solution forms insoluble precipitates. However, the formation of foam by the soap solution is hardly influenced by the presence of sodium sulphate and magnesium sulphate. Thus, on shaking each of the test tubes well, the student observes a good amount of lather in the test tubes marked $P$ and $Q$. Hence, the correct option is $A$.
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MCQ 131 Mark
A student takes about $2 mL$ ethanoic acid in a dry test tube and adds a pinch of sodium hydrogen carbonate to it. He reports the following observations:
  1. Immediately a colourless and odourless gas evolves with a brisk effervescence.
  2. The gas turns lime water milky when passed through it.
  3. The gas burns with an explosion when a burning splinter is brought near it.
  4. The gas extinguishes the burning splinter that is brought near it.
The correct observations are:
  • A
    $\ce{I, II}$ and $\ce{III}$
  • B
    $\ce{II, III}$ and $\ce{IV}$
  • C
    $\ce{III, IV}$ and $\ce{I}$
  • ✓
    $\ce{I, II}$ and $\ce{IV}$
Answer
Correct option: D.
$\ce{I, II}$ and $\ce{IV}$
The correct answer is: option $(d)$ when acetic acid is added to $\mathrm{NaHCO}_3$ solution, and when a burning splinter is brought near the mouth of each test tube, the splinter would be extinguished due to the evolution of carbon dioxide gas with brisk effervescence from the test tube.
$\mathrm{CH}_3 \mathrm{COOH}+\mathrm{NaHCO}_3 \rightarrow \mathrm{CH}_3 \mathrm{COONa}+\mathrm{H}_2 \mathrm{O}+\mathrm{CO}_2$
 
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MCQ 141 Mark
Select the correct observation about dilute solution of acetic acid :
  • A
    It smells like rotten egg and turns blue litmus red.
  • B
    It smells like vinegar and turns red litmus blue.
  • C
    It smells like rotten egg and turns red litmus blue.
  • ✓
    It smells like vinegar and turns blue litmus red.
Answer
Correct option: D.
It smells like vinegar and turns blue litmus red.
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MCQ 151 Mark
Which one of the following sets of materials can be used to prepare soap?
  • A
    Neem oil and calcium hydroxide.
  • ✓
    Castor oil and sodium hydroxide.
  • C
    Mineral oil and sodium hydroxide.
  • D
    Neem oil and magnesium hydroxide.
Answer
Correct option: B.
Castor oil and sodium hydroxide.
Castor oil adds lather and moisturizing properties to the soap, whereas turpentine oil is more used for medicinal purposes. Calcium salts are not used for soaps as they form insoluble scum.
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MCQ 161 Mark
A student took four test tubes $P, Q, R$ and $S$ and filled about $8 mL$ of distilled water in each. After that he dissolved an equal amount of $\mathrm{Na}_2 \mathrm{SO}_4$ in $\mathrm{P}, \mathrm{K}_2 \mathrm{SO}_4$ in $\mathrm{Q}, \mathrm{CaSO}_4$ in $R$ and $\mathrm{MgSO}_4$ in $S$ . On adding an equal amount of soap solution and shaking each test tube well, a good amount of lather will be obtained in the test tubes:
  • A
    $P$ and $Q$
  • B
    $P$ and $R$
  • C
    $P, Q$ and $S$
  • ✓
    $Q, R$ and $S$
Answer
Correct option: D.
$Q, R$ and $S$
Soaps do not form lather with hard water $($water containing calcium and magnesium ions$)$. Among the given test tubes, test tubes $R$ and $S$ contain calcium and magnesium ions, respectively. So the addition of soap solution in these will not produce lather.
On the other hand, water present in test tubes $P$ and $Q$ are soft water $($containing sodium and potassium ions$),$ so the addition of soap solution in these will produce a good amount of lather.
Hence, the correct answer is $P$ and $Q$
Hence, the correct answer is the option $(d)$.
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MCQ 171 Mark
Which of the following sets of materials can be used for conducting a saponification reaction for the preparation of soap?
  • A
    $\mathrm{Ca}(\mathrm{OH})_2$ and neem oil.
  • ✓
    $\ce{NaOH}$ and neem oil.
  • C
    $\ce{NaOH}$ and mineral oil.
  • D
    $\mathrm{Ca}(\mathrm{OH})_2$ and mineral oil.
Answer
Correct option: B.
$\ce{NaOH}$ and neem oil.
Saponification is the chemical reaction that occurs between sodium hydroxide or potassium hydroxide with any kind of fat. In the preparation of soap, saponification occurs when a strong alkali reacts with vegetable oil $($or animal fat$)$. As far as your question is concerned, the choice is pretty simple. You can always use $\ce{NaOH}$ and neem oil for the saponification process in the preparation of soap. Mineral oil cannot be used for the reaction as the resulting soap will become oily or greasy. So, the correct answer is $(B)\ \ce{NaOH}$ and neem oil.
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MCQ 181 Mark
Hard water is not available for an experiment. Some salts are given below:
  1. Sodium chloride.
  2. Sodium sulphate.
  3. Calcium chloride.
  4. Calcium sulphate.
  5. Potassium chloride.
  6. Magnesium sulphate.
Select from the following a group of these salts, each member of which may be dissolved in water to make it hard.
  • A
    $\ce{I, II, V.}$
  • B
    $\ce{I, III, V.}$
  • ✓
    $\ce{III, IV, VI}.$
  • D
    $\ce{II, IV, VI}.$
Answer
Correct option: C.
$\ce{III, IV, VI}.$
Hard water contains $\mathrm{Ca}^{2+}$ and $\mathrm{Mg}^{2+}$ ions.
So, the salts that can be added to water to make it hard are calcium sulphate, calcium chloride and magnesium chloride.
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MCQ 191 Mark
A student prepared $20\%$ sodium hydroxide solution in a beaker to study saponification reaction. Some observations related to this are given below:
  1. Sodium hydroxide solution turns red litmus blue.
  2. Sodium hydroxide readily dissolves in water.
  3. The beaker containing solution appears cold when touched from outside.
  4. The blue litmus paper turns red when dipped into the solution.
The correct observations are:
  • A
    $\ce{I, II}$ and $\ce{IV.}$
  • B
    $\ce{I, II}$ and $\ce{III}.$
  • C
    only $\ce{III}$ and $\ce{IV}.$
  • ✓
    only $\ce{I}$ and $\ce{II}.$
Answer
Correct option: D.
only $\ce{I}$ and $\ce{II}.$
$\ce{NaOH}$ is a base and it turns red litmus blue it dissolves in water. it is exothermic reaction so the beaker become hot when touch.
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MCQ 201 Mark
In order to study saponification reaction we first prepare $20\%$ solution of sodium hydroxide. If we record the temperature of this solution just after adding sodium hydroxide flakes to water and also test its nature using litmus, it may be concluded that the process of making this solution is:
  • ✓
    Exothermic and the solution is alkaline.
  • B
    Endothermic and the solution is alkaline.
  • C
    Endothermic and the solution is acidic.
  • D
    Exothermic and the solution is acidic.
Answer
Correct option: A.
Exothermic and the solution is alkaline.
The reaction of Sodium hydroxide with water is an exothermic reaction. As Sodium hydroxide is base, its aqueous solution is basic in nature. i.e., its alkaline solution. The alkaline nature of the solution is proved by litmus test. Turn red litmus paper blue.
$\mathrm{NaOH}+\mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{Na}^{+}+\mathrm{OH}^{-}+\mathrm{H}_2 \mathrm{O}+$ Heat
$\mathrm{NaOH}+\mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{Na}^{+}+\mathrm{OH}^{-}+\mathrm{H}_2 \mathrm{O}+$ Heat
Thus option $(A)$ is correct statement.
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MCQ 211 Mark
When you add about $2 ml$ of acetic acid to a test tube containing an equal amount of distilled water and leave the test tube to settle after shaking its contents, then after about 5 minutes what will you observe in the test tube:
  • A
    A white precipitate settling at its bottom.
  • ✓
    A clear colourless solution.
  • C
    A layer of water over the layer of acetic acid.
  • D
    A layer of acetic acid over the layer of water.
Answer
Correct option: B.
A clear colourless solution.
Acetic or ethanoic acid is soluble in water in any proportion or ratio.
So no precipitation occurs it dissolves in it, leaving a colorless liquid.
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MCQ 221 Mark
While studying saponification reaction for the preparation of soap, the teacher suggested to a student to add a small quantity of common salt to the reaction mixture. The function of common salt in this reaction is to :
  • A
    Reduce the alkalinity of the soap.
  • B
    Reduce the acidity of the soap.
  • C
    Enhance the cleansing capacity of soap.
  • ✓
    Favour precipitation of soap.
Answer
Correct option: D.
Favour precipitation of soap.
The correct option is $D$.
Common salt is added in saponification reaction because it helps in the precipitation of soap by decreasing its solubility.
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MCQ 231 Mark
A student adds a few drops of ethanoic acid to test tubes $X, Y$ and $Z$ containing aqueous solutions of sodium chloride, sodium hydroxide and sodium carbonate respectively. If he now brings a burning splinter near the mouth of the test tubes immediately after adding the ethanoic acid in each one of them, in which of the test tube or test tubes the flame gets extinguished?
  • A
    $X$ and $Y$
  • B
    $Y$ and $Z$
  • C
    $X$ and $Z$
  • ✓
    Only $Z$
Answer
Correct option: D.
Only $Z$
The chemical reactions in test tubes $X, Y$ and $Z$ can be written as:
Test tube $X:$
$\mathrm{CH}_3 \mathrm{COOH}+\mathrm{NaCl} \rightarrow$ No reaction
Test tube $Y$ :
$\mathrm{CH}_3 \mathrm{COOH}+\mathrm{NaOH} \rightarrow \mathrm{CH}_3 \mathrm{COONa}+\mathrm{H}_2 \mathrm{O}$
Test tube $Z:$
$2 \mathrm{CH}_3 \mathrm{COOH}+\mathrm{Na}_2 \mathrm{CO}_3 \rightarrow 2 \mathrm{CH}_3 \mathrm{COONa}+\mathrm{CO}_2+\mathrm{H}_2 \mathrm{O}$
Thus, the flame will be extinguished when test tube $Z$ is brought near a burning splinter due to evolution of carbon dioxide gas, which does not support combustion.
Hence, the correct option is $D$
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MCQ 241 Mark
Consider the following comments about saponification reactions:
  1. Heat is evolved in these reactions.
  2. For quick precipitation of soap sodium chloride is added to the reaction mixture.
  3. Saponification reactions are special kind of neutralisation reactions.
  4. Soaps are basic salts of long chain fatty acids.
The correct comments are:
  • A
    $\ce{I, II}$ and $\ce{III}.$
  • B
    $\ce{II, III}$ and $\ce{IV.}$
  • ✓
    $\ce{I, II}$ and $\ce{IV}.$
  • D
    Only $\ce{I}$ and $\ce{IV}.$
Answer
Correct option: C.
$\ce{I, II}$ and $\ce{IV}.$
Saponification is a hydrolysis reaction not a neutralization reaction since it does not lead to formation of any water molecule.
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MCQ 251 Mark
A student takes four test tubes marked $P, Q, R$ and $S$ of $25 mL$ capacity and fill $10 mL$ of distilled water in each. He dissolves one spoon full of four different salts in each as $-\ce{KCl}$ in $\mathrm{P}, \mathrm{NaCl}$ in $\mathrm{Q}, \mathrm{CaCl}_2$ in $R$ and $\mathrm{MgCl}_2$ in $S$ . He then adds about $2 mL$ of a sample of soap solution to each of the above test tubes. On shaking the contents of each of the test tubes, he is likely to observe a good amount of lather $($foam$)$ in the test tubes marked :
  • ✓
    $P$ and $Q.$
  • B
    $R$ and $S.$
  • C
    $P, Q$ and $R.$
  • D
    $P, Q$ and $S.$
Answer
Correct option: A.
$P$ and $Q.$
Soap molecules are sodium or potassium salts of long $-$ chain carboxylic acids. On reaction with calcium or magnesium ions, the soap solution forms insoluble precipitates. However, the formation of foam by the soap solution is hardly influenced by the presence of sodium sulphate and magnesium sulphate. Thus, on shaking each of the test tubes well, the student observes a good amount of lather in the test tubes marked $P$ and $Q.$ Hence, the correct option is $A$.
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MCQ 261 Mark
A student adds $2 mL$ of acetic acid to a test tube containing $2 mL$ of distilled water. He then shakes the test tube well and leaves it to settle for some time. After about $5$ minutes he observes that in the test tube there is :
  • ✓
    A clear transparent colourless solution.
  • B
    A clear transparent pink solution.
  • C
    A precipitate settling at the bottom of the test tube.
  • D
    A layer of water over the layer of acetic acid.
Answer
Correct option: A.
A clear transparent colourless solution.
Acetic acid dissolves completely in distilled water and gives a clear, colorless and transparent solution. Hence, the correct option is $A.$
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MCQ 271 Mark
A student adds a few drops of ethanoic acid to test tubes $X, Y$ and $Z$ containing aqueous solutions of sodium chloride, sodium hydroxide and sodium carbonate respectively. If he now brings a burning splinter near the mouth of the test tubes immediately after adding the ethanoic acid in each one of them, in which of the test tube or test tubes the flame gets extinguished?
  • A
    $X$ and $Y$
  • B
    $Y$ and $Z$
  • C
    $X$ and $Z$
  • ✓
    Only $Z$
Answer
Correct option: D.
Only $Z$
The chemical reactions in test tubes $\mathrm{X}, \mathrm{Y}$ and $Z$ can be written as:
Test tube $X:$
$\mathrm{CH}_3 \mathrm{COOH}+\mathrm{NaCl} \rightarrow$ No reaction
Test tube $Y:$
$\mathrm{CH}_3 \mathrm{COOH}+\mathrm{NaOH} \rightarrow \mathrm{CH}_3 \mathrm{COONa}+\mathrm{H}_2 \mathrm{O}$
Test tube $Z:$
$2 \mathrm{CH}_3 \mathrm{COOH}+\mathrm{Na}_2 \mathrm{CO}_3 \rightarrow 2 \mathrm{CH}_3 \mathrm{COONa}+\mathrm{CO}_2+\mathrm{H}_2 \mathrm{O}$
Thus, the flame will be extinguished when test tube $Z$ is brought near a burning splinter due to evolution of carbon dioxide gas, which does not support combustion.
Hence, the correct option is $D.$
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MCQ 281 Mark
In order to study saponification reaction we first prepare $20\%$ solution of sodium hydroxide. If we record the temperature of this solution just after adding sodium hydroxide flakes to water and also test its nature using litmus, it may be concluded that the process of making this solution is :
  • ✓
    Exothermic and the solution is alkaline.
  • B
    Endothermic and the solution is alkaline.
  • C
    Endothermic and the solution is acidic.
  • D
    Exothermic and the solution is acidic.
Answer
Correct option: A.
Exothermic and the solution is alkaline.
The reaction of Sodium hydroxide with water is an exothermic reaction. As Sodium hydroxide is base, its aqueous solution is basic in nature. i.e. its alkaline solution. The alkaline nature of the solution is proved by litmus test. Turn red litmus paper blue.
$\mathrm{NaOH}+\mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{Na}^{+}+\mathrm{OH}^{-}+\mathrm{H}_2 \mathrm{O}+\text { Heat }$
$\mathrm{NaOH}+\mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{Na}^{+}+\mathrm{OH}^{-}+\mathrm{H}_2 \mathrm{O}+\text { Heat }$
Thus option $(A)$ is correct statement.
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MCQ 291 Mark
A student takes about $6 ml$ of distilled water in each of the four test tubes $P, Q, R$ and $S,$ then dissolves an equal amount of four different salts namely sodium chloride in $'P\ ',$ potassium chloride in $'Q\ ',$ calcium chloride in $'R\ '$ Cand magnesium chloride in $'S\ '$. He then adds $10$ drops of soap solution to each test tube and shakes its contents. The test tubes in which scum $($insoluble substance$)$ is formed with soap are:
  • A
    $P$ and $Q$
  • B
    $Q$ and $R$
  • ✓
    $R$ and $S$
  • D
    $Q$ and $S$
Answer
Correct option: C.
$R$ and $S$
Analogous organs are that which are different in origin but similar in function.
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MCQ 301 Mark
For demonstrating the preparation of soap in the laboratory which of the following combinations of an oil and a base would be most suitable?
  • A
    Mustard oil and calcium hydroxide.
  • B
    Castor oil and calcium hydroxide.
  • C
    Turpentine oil and sodium hydroxide.
  • ✓
    Mustard oil and sodium hydroxide.
Answer
Correct option: D.
Mustard oil and sodium hydroxide.
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MCQ 311 Mark
A student adds $2mL$ of acetic acid to a test tube containing $2mL$ of distilled water. He then shakes the test tube well and leaves it to settle for some time. After about $5$ minutes he observes that in the test tube there is :​​​​​​​
  • ✓
    A clear transparent colourless solution
  • B
    A clear transparent pink solution
  • C
    A precipitate settling at the bottom of the test tube.
  • D
    Alayer of water over the layer of acetic acid.
Answer
Correct option: A.
A clear transparent colourless solution
Acetic acid dissolves completely in distilled water and gives a clear, colourless and transparent solution. Hence, the correct option is $A.$
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MCQ 321 Mark
A student adds a few drops of ethanol acid to test tubes $X, Y$ and $Z$ containing aqueous solutions of sodium chloride, sodium hydroxide and sodium carbonate respectively. If he now brings a burning splinter near the mouth of the test tubes immediately after adding the ethanol acid in each one of them, in which of the test tube or test tubes the flame gets extinguished?
  • A
    $X$ and $Y$
  • B
    $Y$ and $Z$
  • C
    $X$ and $Z$
  • ✓
    Only $Z$
Answer
Correct option: D.
Only $Z$
The chemical reactions in test tubes $\mathrm{X}, \mathrm{Y}$ and $Z$ can be written as:
Test tube $X:$
$\mathrm{CH}_3 \mathrm{COOH}+\mathrm{NaCl} \rightarrow$ No reaction
Test tube $Y$ :
$\mathrm{CH}_3 \mathrm{COOH}+\mathrm{NaOH} \rightarrow \mathrm{CH}_3 \mathrm{COONa}+\mathrm{H}_2 \mathrm{O}$
Test tube $Z:$
$2 \mathrm{CH}_3 \mathrm{COOH}+\mathrm{Na} 2 \mathrm{CO} 3 \rightarrow 2 \mathrm{CH}_3 \mathrm{COONa}+\mathrm{CO}_2+\mathrm{H}_2 \mathrm{O}$
Thus, the flame will be extinguished when test tube $Z$ is brought near a burning splinter due to evolution of carbon dioxide gas, which does not support combustion.
Hence, the correct option is $D.$
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MCQ 331 Mark
In order to study personification reaction we first prepare $20\%$ solution of sodium hydroxide. If we record the temperature of this solution just after adding sodium hydroxide flakes to water and also test its nature using litmus, it may be concluded that the process of making this solution is:
  • ✓
    Exothermic and the solution is alkaline.
  • B
    Endothermic and the solution is alkaline.
  • C
    Endothermic and the solution is acidic.
  • D
    Exothermic and the solution is acidic.
Answer
Correct option: A.
Exothermic and the solution is alkaline.
The reaction of Sodium hydroxide with water is an exothermic reaction. As Sodium hydroxide is base, its aqueous solution is basic in nature. i.e. its alkaline solution. The alkaline nature of the solution is proved by litmus test. Turn red litmus paper blue.
$\mathrm{NaOH}+\mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{Na}^{+}+\mathrm{OH}^{-}+\mathrm{H}_2 \mathrm{O}+$ Heat
Thus option $(A)$ is correct statement.
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MCQ 341 Mark
When sodium hydrogen carbonate is added to ethanoic acid a gas evolves. Consider the following statements about the gas evolved?
  • It turns lime water milky.
  • It is evolved with a brisk effervescence.
  • It has a smell of burning sulphur.
  • It is also a by $-$ product of respiration.
The correct statements are:
  • A
    $(A)$ and $(B)$ only.
  • B
    $(B)$ and $(D)$ only.
  • C
    $(A), (C)$ and $(D)$.
  • ✓
    $(A), (B)$ and $(D).$
Answer
Correct option: D.
$(A), (B)$ and $(D).$
When sodium carbonate is reacted with ethanoic acid it forms sodium ethanoate, water, and carbon dioxide gas. Carbon dioxide can be identified by the brisk effervescence. It turns lime water milky and is also a byproduct of respiration.
$\text{CH}_3\text{COOH}+\text{NaHCO}_3\rightarrow\text{CH}_3\text{COONa}+\text{H}_2\text{O}+\text{CO} _2.$
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MCQ 351 Mark
Vinegar is a solution of about :
  • A
    $5$ to $8$ per cent ethanoic acid in alcohol.
  • ✓
    $5$ to $8$ per cent ethanoic acid in water.
  • C
    $50$ to $80$ per cent ethanoic acid in water.
  • D
    $50$ to $80$ per cent ethanoic acid in alcohol.
Answer
Correct option: B.
$5$ to $8$ per cent ethanoic acid in water.
Vinegar is a solution comprising $5$ to $8$ percent ethanoic acids mixed with water.
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MCQ 361 Mark
Soaps are formed by the saponification of :
  • A
    Alcohols
  • B
    Simple ester
  • C
    Carboxylic acids
  • ✓
    Glycerides
Answer
Correct option: D.
Glycerides
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MCQ 371 Mark
When ethanol reacts with sodium metal, it forms two products. These products are :
  • A
    Sodium ethanaoate and oxygen.
  • B
    Sodium ethanaoate and hydrogen.
  • C
    Sodium ethoxide and oxygen.
  • ✓
    Sodium ethoxide and hydrogen.
Answer
Correct option: D.
Sodium ethoxide and hydrogen.
When ethanol reacts with sodium, sodium ethoxide is formed and hydrogen gas is evolved.
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MCQ 381 Mark
Which of the following are correct structural isomers of butane?
  • A
    $1$ and $3$
  • B
    $2$ and $4$
  • ✓
    $1$ and $2$
  • D
    $3$ and $4$
Answer
Correct option: C.
$1$ and $2$
Formula of butane is $\mathrm{C}_4 \mathrm{H}_{10}$. Options $\ce{(iii)}$ and $\ce{(iv)}$ have $8$ hydrogen atoms each, hence, they are incorrect.
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MCQ 391 Mark
$\text{CH}_3\text{CH}_2\text{OH}\xrightarrow[\text{Heat}]{\text{Alkaline KMnO}_4}\text{CH}_3\text{COOH}$In the above given reaction, alkaline $\mathrm{KMnO}_4$ acts as :
  • A
    Reducing agent.
  • ✓
    Oxidising agent.
  • C
    Catalyst.
  • D
    Dehydrating agent.
Answer
Correct option: B.
Oxidising agent.
Alkaline $\mathrm{KMnO}_4$ is also known as Baeyer’s reagent. It acts as an oxidizing agent.
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MCQ 401 Mark
Hydrogen chloride molecule contains :
  • ✓
    Covalent bond
  • B
    Ionic bond
  • C
    Co - ordinate covalent bond
  • D
    Vander waal bond
Answer
Correct option: A.
Covalent bond
$\ce{H − Cl}$ bond is a covalent bond.
A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms.
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MCQ 411 Mark
In a soap micelle, the soap molecules are arranged radially with :
  • A
    Ionic ends directed towards the centre and hydrocarbon ends directed outwards.
  • ✓
    Hydrocarbon ends directed towards the centre and ionic ends directed outwards.
  • C
    Both ionic ends and hydrocarbon ends directed toward the centre.
  • D
    Both hydrocarbon ends and ionic ends directed outwards
Answer
Correct option: B.
Hydrocarbon ends directed towards the centre and ionic ends directed outwards.
In a soap micelle, the soap molecules are arranged radially with the hydrocarbon ends, i.e. hydrophobic, directed towards the centre; and, ionic ends, i.e. hydrophilic, directed outwards.
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MCQ 421 Mark
The hydrocarbon which has alternate single and double bonds arranged in the form of a ring is :
  • A
    Cyclobutane.
  • ✓
    Benzene.
  • C
    Butene.
  • D
    Hexene.
Answer
Correct option: B.
Benzene.
Benzene is the hydrocarbon which has alternate single and double bonds arranged in the form of a ring.
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MCQ 441 Mark
When ethanoic acid is treated with $\ce{NaHCO}$ the gas evolved is :
  • A
    $\mathrm{H}_2$
  • ✓
    $\mathrm{CO}_2$
  • C
    $\mathrm{CH}_4$
  • D
    $\mathrm{CO}$
Answer
Correct option: B.
$\mathrm{CO}_2$
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MCQ 451 Mark
The name of the compound $\text{CH}_3-\text{CH}_2-\text{CHO}$ is :
  • ✓
    Propanal.
  • B
    Propanone.
  • C
    Ethanol.
  • D
    Ethanal.
Answer
Correct option: A.
Propanal.
Compound contains three carbon atoms so prop $-$ would be root word and $– \ce{CHO}$ functional group so suffix will be $–\ \ce{ al}$. Hence name would be propane $+ \ \ce{al} =$ propanal.
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MCQ 461 Mark
The molecular formula of an organic compound is $\mathrm{C}_{48} \mathrm{H}_{94}$. This compound belongs to the homologous series of :
  • A
    Alkenes.
  • B
    Aldehydes.
  • ✓
    Alkynes.
  • D
    Alkanes.
Answer
Correct option: C.
Alkynes.
The compound $\mathrm{C}_{48} \mathrm{H}_{94}$ belongs to the homologous series of alkynes, as it satisfies the general formula $\mathrm{C}_n \mathrm{H}_{2 n-2}$.
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MCQ 471 Mark
The chemical which is not required for the preparation of soap in the laboratory is :
  • A
    Vegetable oil.
  • ✓
    Baking soda.
  • C
    Caustic soda.
  • D
    Common salt.
Answer
Correct option: B.
Baking soda.
Baking soda is not required for the preparation of soap in the laboratory. For the preparation of soap, vegetable oil, caustic soda and common salt are needed.
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MCQ 481 Mark
Which of the following are members of same homologous series?
  • ✓
    $\mathrm{HCOOCH}_3$ and $\mathrm{CH}_3 \mathrm{COOCH}_3$
  • B
    $\ce{HCOOH}$ and $\ce{HCOOCH}$
  • C
    $\mathrm{CH}_3 \mathrm{COCH}$ and $\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CHO}$
  • D
    $\mathrm{C}_2 \mathrm{H}_2 \mathrm{OH}$ and $\mathrm{CH}_3 \mathrm{OCH}_3$
Answer
Correct option: A.
$\mathrm{HCOOCH}_3$ and $\mathrm{CH}_3 \mathrm{COOCH}_3$
The iupac name of $\mathrm{CH}_3 \mathrm{COOCH}_3$ is methyl ethanoate or methyl acetate.
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MCQ 491 Mark
The organic compound prepared by Wohler from an inorganic compound called ammonium cyanate was :
  • A
    Glucose.
  • ✓
    Urea.
  • C
    Uric acid.
  • D
    Vinegar.
Answer
Correct option: B.
Urea.
Urea is the organic compound prepared by Wohler from an inorganic compound called ammonium cyanate.
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MCQ 501 Mark
Ethane, with the molecular formula $\mathrm{C}_2 \mathrm{H}_6$ has :
  • A
    $6$ covalent bonds.
  • ✓
    $7$ covalent bonds.
  • C
    $8$ covalent bonds.
  • D
    $9$ covalent bonds.
Answer
Correct option: B.
$7$ covalent bonds.
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M.C.Q - Science STD 10 Questions - Vidyadip