Acids, Bases and Salts: Class 10 Science Q&A
77 free answers on Acids, Bases and Salts (Science) for Class 10 students, across CBSE, ICSE and State boards. Includes questions such as “How would you distinguish between baking powder and washing soda by heating?”, “What happens when nitric acid is added to egg shell?”
Question & Answer
Questions
- ScienceClass 10CBSE
A sulphate salt of Group 2 element of the Periodic Table is a white, soft substance, which can be moulded into different shapes by making its dough. When this compound is left in open for some time, it becomes a solid mass and cannot be used for moulding purposes. Identify the sulphate salt and why does it show such a behaviour? Give the reaction involved.
Soln: The sulphate salt should be calcium sulphate which is white and soft substance. Calcium sulphate is popularly known as plaster of paris. Plaster of paris has half molecule of water of crystallization. When we leave plaster of paris open for some time, it absorbs moisture to gain number of molecules of crystallization. This newly formed compound is called Gypsum which is hard to make moulds.
- ScienceClass 10CBSE
A dry pellet of a common base B, when kept in open absorbs moisture and turns sticky. The compound is also a by–product of chloralkali process. Identify B. What type of reaction occurs when B is treated with an acidic oxide? Write a balanced chemical equation for one such solution.
Soln: A compound which is a byproduct of chloralkali process is NaOH. Hence compound B is NaOH. When NaOH is treated with acidic oxide neutralization process occurs. For Example If NaOH is treated with carbon-di-oxide, it gives Sodium carbonate. 2NaOH+ CO2 Na2CO3+ H2O
- ScienceClass 10CBSE
A metal carbonate X on reacting with an acid gives a gas which when passed through a solution Y gives the carbonate back. On the other hand, a gas G that is obtained at anode during electrolysis of brine is passed on dry Y, it gives a compound Z, used for disinfecting drinking water. Identity X, Y, G and Z.
Soln: X is Calcium . When calcium carbonate reacts with HCl it gives out CO2 gas. CaCO3 + HCl CaCl2+CO2+H2O When CO2 is passed into lime water it turns milky due to formation of Calcium carbonate. Hence solution Y is lime water When chlorine gas is passed on dry lime water it gives bleaching powder which is used for disinfecting water.
- ScienceClass 10CBSE
When zinc metal is treated with a dilute solution of a strong acid, a gas is evolved, which is utilised in the hydrogenation of oil. Name the gas evolved. Write the chemical equation of the reaction involved and also write a test to detect the gas formed.
Soln: When Zinc reacts with Dilute acid solution, following reaction takes place Hydrogen gas is evolved Zn + 2HCl ZnCl2 + H2 When Hydrogen gas is brought near Burning flame, pop pops up which is the confirmation for evolution of Hydrogen gas.
- ScienceClass 10CBSE
Fill in the missing data in the following table Salted Obtained from Name of the Salt Formula Base Acid Ammonium chloride NH4Cl NH4OH - Copper sulphate - - H2 SO4 Sodium chloride NaCl NaOH - Magnesium nitrate Mg (NO3 ) 2 - HNO3 Potassium sulphate K2 SO4 - - Calcium nitrate Ca(NO3 ) 2 Ca(OH)2 -
Soln: Salted Obtained from Name of the Salt Formula Base Acid Ammonium chloride NH4Cl NH4OH HCl <
- ScienceClass 10CBSE
What are strong and weak acids? In the following list of acids, separate strong acids from weak acids. Hydrochloric acid, citric acid, acetic acid, nitric acid, formic acid, sulphuric acid.
Strong acids are those which gets completely ionized and weak acids are those which gets partially ionized. Hydrochloric acid- Strong Acid citric acid- Weak Acid acetic acid- Weak Acid nitric acid, - Strong Acid formic acid- Weak Acid sulphuric acid- Strong Acid
- ScienceClass 10CBSE
In one of the industrial processes used for manufacture of sodium hydroxide, a gas X is formed as by product. The gas X reacts with lime water to give a compound Y which is used as a bleaching agent in chemical industry. Identify X and Y giving the chemical equation of the reactions involved.
Soln: X = Chlorine (Cl 2) Y = Bleaching powder (CaOCl2) Ca(OH)2 (s) + Cl2 (g) → CaOCl2 (s) + H2O — Calcium oxychloride (bleaching powder)
- ScienceClass 10CBSE
Salt A commonly used in bakery products on heating gets converted into another salt B which itself is used for removal of hardness of water and a gas C is evolved. The gas C when passed through lime water, turns it milky. Identify A, B and C.
Soln: Salt A is Baking soda (Sodium Hydrogen Carbonate) which will turn to Sodium carbonate( Salt B) on heating. Gas C turn lime water milky hence it must be CO2.
- ScienceClass 10CBSE
How would you distinguish between baking powder and washing soda by heating?
Soln: When we heat baking powder CO2 is released which can be confirmed by passing evolved gas into lime water which will turn milky. This reaction will not happen when you heat washing soda.
- ScienceClass 10CBSE
A student prepared solutions of (i) an acid and (ii) a base in two separate beakers. She forgot to label the solutions and litmus paper is not available in the laboratory. Since both the solutions are colourless, how will she distinguish between the two?
Soln: Student can use Phenopthalein indicator to check the nature of the solution.
- ScienceClass 10CBSE
What happens when nitric acid is added to egg shell?
Nitric acid dissolved the egg shell, which is made up of Calcium carbonate. Calcium carbonate, on reacting with nitric acid, yields calcium nitrate and carbon dioxide gas.When nitric acid is added to an eggshell:The eggshell is mainly made of calcium carbonate (CaCO₃).Nitric acid reacts with calcium carbonate in a chemical reaction</s
- ScienceClass 10CBSE
Name the acid present in ant sting and give its chemical formula. Also give the common method to get relief from the discomfort caused by the ant sting.
Soln: Ant sting release methanoic acid. Chemical formula of methanoic acid is HCOOH. If we rub baking soda on the affected area it can give relief from the discomfort caused by ant sting.
- ScienceClass 10CBSE
What will be the action of the following substances on litmus paper? Dry HCl gas, Moistened NH3 gas, Lemon juice, Carbonated soft drink, Curd, Soap solution.
Soln: Dry HCl gas- No effect Moistened NH3 gas- Turns litmus paper to blue colour Lemon juice- Turns litmus paper to red colour Carbonated soft drink- Turns litmus paper to red colour Curd- Turns litmus paper to red colour Soap solution- Turns litmus paper to blue colour
- ScienceClass 10CBSE
Match the important chemicals given in Column (A) with the chemical formulae given in Column (B) Column (A) Column (B) (a) Plaster of Paris (i) Ca(OH)2 (b) Gypsum (ii) CaSO4. ½ H2O (c) Bleaching Powder (iii)CaSO4.2H2O (d) Slaked Lime (iv) CaOCl2
Soln: Column (A) Column (B) (a) Plaster of Paris (ii) CaSO4. ½ H2O (b) Gypsum (iii)CaSO4.2H2O (c) Bleaching Powder
- ScienceClass 10CBSE
Match the acids given in Column (A) with their correct source given in Column (B) Column (A) Column (B) (a) Lactic acid (i) Tomato (b) Acetic acid (ii) Lemon (c) Citric acid (iii) Vinegar (d) Oxalic acid (iv) Curd
Soln: Column (A) Column (B) (a) Lactic acid (iv) Curd (b) Acetic acid (iii) Vinegar (c) Citric acid (ii) Lemon (d) Oxalic acid
- ScienceClass 10CBSE
Identify the correct representation of reaction occurring during chloralkali process (a) 2NaCl(l) + 2H2O(l) → 2NaOH(l) + Cl2 (g) + H2 (g) (b) 2NaCl(aq) + 2H2O(aq) → 2NaOH(aq) + Cl2 (g) + H2 (g) (c) 2NaCl(aq) + 2H2O(l) → 2NaOH(aq) + Cl2 (aq) + H2 (aq) 2NaCl (aq) + 2H2O (l) → 2NaOH (aq) + Cl2 (g) + H2 (g)
Soln: Answer is (d) 2NaCl (aq) + 2H2O (l) → 2NaOH (aq) + Cl2 (g) + H2 (g)
- ScienceClass 10CBSE
Which of the following are present in a dilute aqueous solution of hydrochloric acid? (a) H3O+ + Cl– (b) H3O+ + OH– (c) Cl– + OH– unionised HCl
Soln: Answer is (a) H3O+ + Cl– Explanation: Acid produces Hydrogen which will combine with water molecule to produce Hydronium ion.
- ScienceClass 10CBSE
Which of the following statements is true for acids? (a) Bitter and change red litmus to blue (b) Sour and change red litmus to blue (c) Sour and change blue litmus to red (d) Bitter and change blue litmus to red
Soln: Answer is (c) Sour and change blue litmus to red
- ScienceClass 10CBSE
Which of the following is(are) true when HCl (g) is passed through water? (i) It does not ionise in the solution as it is a covalent compound. (ii) It ionises in the solution (iii) It gives both hydrogen and hydroxyl ion in the solution (iv) It forms hydronium ion in the solution due to the combination of hydrogen ion with water molecule (a) (i) only (b) (iii) only (c) (ii) and (iv) (iii) and (iv)
Soln: Answer is (c) (ii) and (iv) Explanation: HCL is a strong acid which ionizes completely in water to produce Hydrogen as well as Hydrogen and chlorine. Hydrogen produces combine with water molecules to give Hydronium ions.
- ScienceClass 10CBSE
Match the chemical substances given in Column (A) with their appropriate application given in Column (B) Column (A) Column (B) (A) Bleaching powder (i) Preparation of glass (B) Baking soda (ii) Production of H2 and Cl2 (C) Washing soda (iii) Decolourisation (D) Sodium chloride (iv) Antacid (a) A—(ii), B—(i), C—(iv), D—(iii) (b) A—(iii), B—(ii), C—(iv), D—(i) (c) A—(iii), B—(iv), C—(i), D—(ii) (d) A—(ii), B—(iv), C—(i), D—(iii)
Answer is (c) A—(iii), B—(iv), C—(i), D—(ii)