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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.

Answer: When dilute acid reacts with Zinc metal, hydrogen gas is liberated. Zn + HCl → H2 + ZnCl2 Zinc reacts easily with... View Article

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.

Answer: Acid strength is the measure of the ability of the acid to lose its H+ ion. A strong acid... View Article

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 – – H2SO4... View Article

In one of the industrial processes used for the manufacture of sodium hydroxide, a gas X is formed as a by-product. The gas X reacts with lime water to give a compound Y which is used as a bleaching agent in the chemical industry. Identify X and Y, giving the chemical equation of the reactions involved.

Answer: X = Chlorine (Cl2) Y = Bleaching powder (CaOCl2) The Chlor-alkali process, which uses sodium chloride to make sodium... View Article

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.

Answer: Salt A is Baking soda (Sodium Hydrogen Carbonate) which will turn to Sodium carbonate( Salt B) on heating. Gas... View Article

How would you distinguish between baking powder and washing soda by heating?

Answer: Baking powder is a mixture of sodium hydrogen carbonate and edible acid-like tartaric acid. It is a raising agent... View Article

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?

Answer: To distinguish between the acid and base in the beaker, use a chemical indicator like phenolphthalein or natural indicators... View Article

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.

Answer: Ant sting release methanoic acid or formic acid. The chemical formula of methanoic acid is HCOOH. If we rub... View Article

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.

Answer: A type of paper that changes colour in response to the acidity of the solution it is dipped in... View Article

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... View Article

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)... View Article

Identify the correct representation of reaction occurring during the 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) (d) 2NaCl (aq) + 2H2O (l) → 2NaOH (aq) + Cl2 (g) + H2 (g)

Answer: (d) 2NaCl(aq) + 2H2O(l) → 2NaOH(aq) + Cl2(g) + H2(g) Chlor-alkali process When electricity is passed through an aqueous... View Article

Which of the following are present in a dilute aqueous solution of hydrochloric acid? (a) H3O+ + Cl– (b) H3O+ + OH– (c) Cl– + OH– (d) unionised HCl

Answer: (a) H3O+ + Cl– Acid produces hydrogen which will combine with a water molecule to produce Hydronium ion. The... View Article

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

Answer: (c) Sour and change blue litmus to red Acids change the colour of the litmus solution from blue to... View Article

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) (d) (iii) and (iv)

Answer: (c) (ii) and (iv) Acid produces hydrogen which will combine with a water molecule to produce Hydronium ions. HCl... View Article

Equal volumes of hydrochloric acid and sodium hydroxide solutions of same concentration are mixed and the pH of the resulting solution is checked with a pH paper. What would be the colour obtained? (You may use colour guide given in Figure (a) Red (b) Yellow (c) Yellowish green (d) Blue

Answer: (c) Yellowish green Here neutralization takes place between HCL and NaOH solution hence PH will remain neutral which will... View Article

Which of the following statements is not correct? (a) All metal carbonates react with acid to give a salt, water and carbon dioxide (b) All metal oxides react with water to give salt and acid (c) Some metals react with acids to give salt and hydrogen (d) Some non-metal oxides react with water to form an acid

Answer: (b) All metal oxides react with water to give salt and acid Metal oxides Metallic oxides are basic in... View Article

In an attempt to demonstrate electrical conductivity through an electrolyte, the following apparatus was set up. Which among the following statement(s) is(are) correct? 1) Bulb will not glow because the electrolyte is not acidic 2) Bulb will glow because NaOH is a strong base and furnishes ions for conduction. 3) Bulb will not glow because the circuit is incomplete 4) Bulb will not glow because it depends upon the type of electrolytic solution (a) (i) and (iii) (b) (ii) and (iv) (c) (ii) only (d) (iv) only

Answer: (c) (ii) only A channel through which electrons travel from a voltage or current source is known as an... View Article

Which of the following substance will not give carbon dioxide on treatment with dilute acid? (a) Marble (b) Limestone (c) Baking soda (d) Lime

Answer: (d) Lime Marble, Limestone and baking soda have carbonates which produces CO2 gas. Lime contains Hydroxide which will not... View Article

Which of the following phenomena occur, when a small amount of acid is added to water? (i) Ionisation (ii) Neutralisation (iii) Dilution (iv) Salt formation (a) (i) and (ii) (b) (i) and (iii) (c) (ii) and (iii) (d) (ii) and (iv)

Answer: (c) Vanilla essence A substance that can be added to the reaction mixture to indicate the equivalence point of... View Article

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