Class 10 Science · Chapter 4

Carbon and its Compounds

442 Class 10 Science questions on Carbon and its Compounds from the NCERT textbook, NCERT Exemplar and CBSE board papers 2017–2026, each with its answer and a step-by-step solution.

CBSE Class 10 Science previous year papers, with answers →

Questions · page 22 of 23

1. Q421 CBSE 2017
   While studying the saponification reaction, what ​do ​you observe when you mix an equal ​amount ​of ​colourless ​vegetable oil and 20% ​aqueous solution of ​NaOH in a beaker ?

   1. (a)The colour of the mixture has become dark brown
   2. (b)A brisk effervescence is taking place in the beaker
   3. (c)The outer surface of the beaker has become hot
   4. (d)The outer surface of the beaker has become cold
   Show answer

   (c) The outer surface of the beaker has become hot

   Step-by-step solution →
2. Q422 CBSE 2017
   What change ​would you observe if you ​put ​a drop ​of dilute acetic acid first ​to ​blue litmus solution and then to red litmus solution ​?

   1. (a)No change in blue ; Red turns blue
   2. (b)Blue turns red ; No change in red
   3. (c)Blue becomes colourless ; Red turns blue
   4. (d)No change in blue ; No change in red
   Show answer

   (b) Blue turns red ; No change in red

   Step-by-step solution →
3. Q423 CBSE 2017
   A student while ​studying a saponification-reaction on ​adding ​20% ​NaOH solution to a colourless vegetable ​oil ​taken in a ​beaker observes that

   1. (a)the outer surface of the beaker becomes cold.
   2. (b)the colour of the mixture becomes brown.
   3. (c)there is a brisk effervescence in the beaker.
   4. (d)the outer surface of the beaker becomes hot.
   Show answer

   (d) the outer surface of the beaker becomes hot.

   Step-by-step solution →
4. Q424 CBSE 2017
   A student is given equal amount of ​three samples of water ​with temporary hardness labelled as ‘A’, ‘B’ ​and ‘C’. He keeps the three samples at different temperatures – A at room temperature, B at $50{}^{\circ }\text{C}$ and C at $95{}^{\circ }\text{C}$. Which sample will give maximum amount of ​lather when $10$ mL of soap ​solution is added to each sample ​and shaken for equal ​time ?

   1. (a)(A) only
   2. (b)Both (A) & (B)
   3. (c)Both (B) and (C)
   4. (d)(C) only
   Show answer

   (d) (C) only

   Step-by-step solution →
5. Q425 CBSE 2017
   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 ${\text{Na}}_2{\text{SO}}_4$ in P, ${\text{K}}_2{\text{SO}}_4$ in Q, ${\text{CaSO}}_4$ in R and ${\text{MgSO}}_4$ 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 :

   1. (a)P and Q
   2. (b)P and R
   3. (c)P, Q and S
   4. (d)Q, R and S
   Show answer

   (a) P and Q

   Step-by-step solution →
6. Q426 CBSE 2017
   If you take some distilled water in a test-tube, add an equal amount of acetic acid to ​it, shake the test-tube well ​and ​leave ​it undisturbed ​on the test-tube stand, then after about 5 ​minutes, what would you observe ​?

   1. (a)There is a layer of water over the layer of acetic acid.
   2. (b)A precipitate is settling at the bottom of the test-tube.
   3. (c)Bubbles of colourless gas are coming out of the test-tube.
   4. (d)There is a clear, colourless transparent solution in the test-tube.
   Show answer

   (d) There is a clear, colourless transparent solution in the test-tube.

   Step-by-step solution →
7. Q427 CBSE 2017
   A student requires hard water for an ​experiment in his laboratory which is not available in the neighbouring ​area. In the laboratory ​there are some salts, ​which when dissolved in distilled ​water can convert it ​into hard ​water. Select from the following groups of salts, a group, each salt of which when dissolved in distilled water will make it hard.

   1. (a)Sodium chloride, Potassium chloride
   2. (b)Sodium sulphate, Potassium sulphate
   3. (c)Sodium sulphate, Calcium sulphate
   4. (d)Calcium sulphate, Calcium chloride
   Show answer

   (d) Calcium sulphate, Calcium chloride

   Step-by-step solution →
8. Q428 CBSE 2017
   Select a ​group from the ​following groups of ​salt, each salt of which on ​dissolving ​in distilled water ​can make it hard ​:

   1. (a)Sodium chloride ; Calcium chloride
   2. (b)Sodium chloride ; Potassium chloride
   3. (c)Calcium chloride ; Magnesium chloride
   4. (d)Magnesium chloride ; Potassium chloride
   Show answer

   (c) Calcium chloride ; Magnesium chloride

   Step-by-step solution →
9. Q429 CBSE 2017
   You have neem oil ​in a beaker. In order ​to ​study ​saponification reaction, which of ​the ​following chemical substances would ​you add to this ​oil ?

   1. (a)20% ${\text{Ca(OH)}}_2$
   2. (b)20% $\text{NaOH}$
   3. (c)30% ${\text{Mg(OH)}}_2$
   4. (d)10% ${\text{Ca(OH)}}_2$
   Show answer

   (b) 20% $\text{NaOH}$

   Step-by-step solution →
10. Q430 CBSE 2017
    Some ​students studied the physical properties of acetic acid and noted ​down their observations. ​Which ​of the ​following observations is ​correct ?

    1. (a)Smells like rose and soluble in water.
    2. (b)Smells like burning plastic and insoluble in water.
    3. (c)Smells like vinegar and soluble in water.
    4. (d)Smells like rotten egg and soluble in water.
    Show answer

    (c) Smells like vinegar and soluble in water.

    Step-by-step solution →
11. Q431 CBSE 2017
    Select ​the ​correct ​statement about ​the properties ​of acetic ​acid.

    1. (a)It smells like vinegar and turns red litmus to blue.
    2. (b)It is insoluble in water and turns blue litmus to red.
    3. (c)It is soluble in water and turns red litmus to blue.
    4. (d)It smells like vinegar and turns blue litmus to red.
    Show answer

    (d) It smells like vinegar and turns blue litmus to red.

    Step-by-step solution →
12. Q432 CBSE 2017
    A student ​wants to prepare soap in the ​laboratory. Which of the ​following sets ​of ​materials he should use ​?

    1. (a)Neem oil and $\text{NaCl}$
    2. (b)Neem oil and ${\text{Na}}_2{\text{CO}}_3$
    3. (c)Mustard oil and $\text{NaOH}$
    4. (d)Mineral oil and $\text{NaOH}$
    Show answer

    (c) Mustard oil and $\text{NaOH}$

    Step-by-step solution →
13. Q433 CBSE 2017
    You have four test ​tubes A, B, C and ​D filled ​with aqueous solution of same concentration but of different salts. In A solution of $\text{NaCl}$, B solution of ${\text{CaCl}}_2$, C solution ​of ${\text{MgCl}}_2$ and D solution of $\text{KCl}$ is filled. If you add equal ​amounts of a soap solution to each test tube and shake the contents well, in which of the ​test tubes will scum (insoluble substance) be obtained ?

    1. (a)A and B
    2. (b)B and C
    3. (c)C and D
    4. (d)A and D
    Show answer

    (b) B and C

    Step-by-step solution →
14. Q434 CBSE 2017
    In an experiment ​to study ​the properties of acetic acid, answer the following questions :

    1. (i)What ​happens when some water is added to the test ​tube containing acetic acid and shaken vigorously ?
    2. (ii)​Blue and red ​litmus papers ​are put in the test tube ​containing a acid one after the other.
    Show answer

    Acetic acid dissolves completely in water; it turns blue litmus red but leaves red litmus unchanged, showing it is an acid.

    (i) The acetic acid dissolves completely in the water: after shaking, the test tube holds one clear, colourless solution with no separate layer, because acetic acid mixes with water in all proportions. (ii) The blue litmus paper turns red and the red litmus paper shows no change (it stays red), which shows that acetic acid is an acid.

    Step-by-step solution →
15. Q435 CBSE 2017
    A gas is liberated immediately with ​a brisk effervescence, ​when you add ​acetic acid to sodium hydrogen ​carbonate powder in a test tube. Name the gas and describe the test that confirms the ​identity ​of ​the gas.
    Show answer

    The gas is carbon dioxide; it turns lime water milky because calcium carbonate forms.

    The gas is carbon dioxide: ${\text{CH}}_3\text{COOH}+{\text{NaHCO}}_3\to {\text{CH}}_3\text{COONa}+{\text{H}}_2\text{O}+{\text{CO}}_2$. Test: pass the gas through lime water (calcium hydroxide solution) using a delivery tube. The lime water turns milky, because a white precipitate of calcium carbonate forms: ${\text{Ca(OH)}}_2+{\text{CO}}_2\to {\text{CaCO}}_3+{\text{H}}_2\text{O}$. This confirms that the gas is carbon dioxide.

    Step-by-step solution →
16. Q436 CBSE 2017
    (A) If you are asked to report your observations about the following two ​properties of acetic acid, what would you report ​?

    1. (i)Odour
    2. (ii)Effect on litmus (B) If you take a pinch of sodium hydrogen carbonate powder in ​a test-tube and add drop-by-drop ​acetic acid to it, what would you ​observe immediately ? ​List any two main observations.
    Show answer

    Acetic acid smells of vinegar and turns blue litmus red; with sodium hydrogen carbonate it gives brisk effervescence of carbon dioxide.

    (A) (i) Acetic acid has a pungent smell of vinegar. (ii) It turns blue litmus red; red litmus stays red. (B) (1) Brisk effervescence: bubbles of gas are given off at once. (2) The gas is colourless and odourless, and it turns lime water milky, showing that it is carbon dioxide: ${\text{CH}}_3\text{COOH}+{\text{NaHCO}}_3\to {\text{CH}}_3\text{COONa}+{\text{H}}_2\text{O}+{\text{CO}}_2$.

    Step-by-step solution →
17. Q437 CBSE 2017
    Mention the essential ​material ​(chemicals) to prepare soap in the laboratory. Describe in brief the test ​of determining ​the nature (acidic/alkaline) ​of ​the reaction mixture of saponification reaction.
    Show answer

    Vegetable oil, sodium hydroxide solution and common salt are needed; red litmus turning blue shows the mixture is alkaline.

    Chemicals: a vegetable oil (or fat), sodium hydroxide solution (about 20%), and common salt (sodium chloride) to separate the soap, with water to dissolve the alkali. Test: dip red and blue litmus paper into a little of the reaction mixture; the red litmus turns blue and the blue litmus stays blue, so the mixture is alkaline (basic).

    Step-by-step solution →
18. Q438 CBSE 2017
    What material do you use to prepare soap in the ​laboratory ? How would you ​test the ​nature (Acidic / ​Basic) of the reaction ​mixture ​?
    Show answer

    Vegetable oil and sodium hydroxide solution (with common salt to separate the soap); red litmus turning blue shows the mixture is basic.

    Material: a vegetable oil (for example castor, cottonseed or coconut oil) and sodium hydroxide solution (about 20%), warmed and stirred together; common salt is added afterwards to make the soap separate out. Test: put a drop of the reaction mixture on red litmus paper and on blue litmus paper. The red litmus turns blue and the blue litmus stays blue, so the reaction mixture is basic.

    Step-by-step solution →
19. Q439 CBSE 2017
    If you add a few drops of acetic acid to a ​test tube ​containing

    1. (i)distillated water and
    2. (ii)aqueous solution of sodium hydrogen carbonate, ​what would ​you observe ? If ​a ​reaction takes place in ​any ​one of the above two cases, list its two observations.
    Show answer

    No reaction with distilled water; with sodium hydrogen carbonate there is brisk effervescence of carbon dioxide, which turns lime water milky.

    (i) With distilled water: the acetic acid dissolves completely, giving a clear, colourless solution; there is no effervescence and no visible reaction. (ii) With sodium hydrogen carbonate solution a reaction takes place: ${\text{CH}}_3\text{COOH}+{\text{NaHCO}}_3\to {\text{CH}}_3\text{COONa}+{\text{H}}_2\text{O}+{\text{CO}}_2$. Its two observations: brisk effervescence, as bubbles of a colourless, odourless gas are given off; and the gas turns lime water milky, showing that it is carbon dioxide.

    Step-by-step solution →
20. Q440 CBSE 2017
    You have four beakers A, B, C and D. Out of A ​and ​B ​one has hard water ​and the other has ​soft water. Out of ​C ​and D one has soap solution and the other has detergent-solution. How would you identify these liquids ​?
    Show answer

    Soap forms curdy scum in hard water but lathers in soft water; detergent lathers in both, which identifies all four.

    Take equal volumes of A and of B in two test tubes each. Add a few drops of C to one tube of A and one of B, and a few drops of D to the other two, and shake all four equally. (i) Soap and detergent: the solution that behaves differently in A and in B, forming a curdy white scum and little lather in one water but plenty of lather in the other, is the soap solution; the other, which lathers well in both waters, is the detergent solution. (ii) Hard and soft water: the water in which the soap forms the curdy scum and little lather is hard water; the water in which the soap lathers readily is soft water. The scum forms because the calcium and magnesium ions of hard water make insoluble salts with soap but not with a detergent.

    Step-by-step solution →