Latest Posts

Which of the following statements is correct about an aqueous solution of an acid and of a base? (i) Higher the pH, stronger the acid (ii) Higher the pH, weaker the acid (iii) Lower the pH, stronger the base (iv) Lower the pH, weaker the base (a) (i) and (iii) (b) (ii) and (iii) (c) (i) and (iv) (d) (ii) and (iv)

Answer: (d) (ii) and (iv) On the PH scale acids are those whose PH is below 7 lower is the... View Article

To protect tooth decay we are advised to brush our teeth regularly. The nature of the toothpaste commonly used is (a) acidic (b) neutral (c) basic (d) corrosive

Answer: (c) basic The nature of toothpaste is alkaline which is basic. They neutralize the acid produced by bacteria in... View Article

One of the constituents of baking powder is sodium hydrogen carbonate, the other constituent is (a) hydrochloric acid (b) tartaric acid (c) acetic acid (d) sulphuric acid

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

Common salt besides being used in the kitchen can also be used as the raw material for making: (i) washing soda (ii) bleaching powder (iii) baking soda (iv) slaked lime (a) (i) and (ii) (b) (i), (ii) and (iv) (c) (i) and (iii) (d) (i), (iii) and (iv)

Answer: (a) (i) and (ii) The chemical formula of common salt is NaCl and the chemical name of common salt... View Article

Sodium hydrogen carbonate, when added to acetic acid, evolves a gas. Which of the following statements are true about the gas evolved? (i) It turns lime water milky (ii) It extinguishes a burning splinter (iii) It dissolves in a solution of sodium hydroxide (iv) It has a pungent odour (a) (i) and (ii) (b) (i), (ii) and (iii) (c) (ii), (iii) and (iv) (d) (i) and (iv)

Answer: (a) (i) and (ii) Reaction between Sodium hydrogen carbonate and acetic acid leads to the evolution of carbon-dioxide gas.... View Article

If a few drops of a concentrated acid accidentally spills over the hand of a student, what should be done? (a) Wash the hand with saline solution (b) Wash the hand immediately with plenty of water and apply a paste of sodium hydrogen carbonate (c) After washing with plenty of water apply a solution of sodium hydroxide on the hand (d) Neutralise the acid with a strong alkali

Answer: (b) Wash the hand immediately with plenty of water and apply a paste of sodium hydrogen carbonate strong Washing... View Article

Which of the following gives the correct increasing order of acidic strength (1) Water < Acetic acid < Hydrochloric acid (2) Water < Hydrochloric acid< Acetic acid (3) Acetic acid< Water < Hydrochloric acid (4) Hydrochloric acid< Water

Answer: (1) Water < Acetic acid < Hydrochloric acid Water is neutral in its pure form, Acetic acid is an... View Article

A sample of soil is mixed with water and allowed to settle. The clear supernatant solution turns the pH paper yellowish-orange. Which of the following would change the colour of this pH paper to greenish-blue? (a) Lemon juice (b) Vinegar (c) Common salt (d) An antacid

Answer:(d) An antacid Sample solution turn pH paper yellowish-orange which confirms the acidic nature of the sample. To make the... View Article

Sodium carbonate is a basic salt because it is a salt of (a) strong acid and strong base (b) weak acid and weak base (c) strong acid and weak base (d) weak acid and strong base

Answer: (d) weak acid and strong base Salt is formed by weak acid and a strong base. Here, Sodium is... View Article

Which of the following salts does not contain water of crystallisation? (a) Blue vitriol (b) Baking soda (c) Washing soda (d) Gypsum

Answer: (b) Baking soda Baking sodas is white amorphous powder whereas other salts given in the question are crystalline in... View Article

During the preparation of hydrogen chloride gas on a humid day, the gas is usually passed through the guard tube containing calcium chloride. The role of calcium chloride taken in the guard tube is to (a) absorb the evolved gas (b) moisten the gas (c) absorb moisture from the gas (d) absorb Cl– ions from the evolved gas

Answer: (c) absorb moisture from the gas Calcium is a good dehydrating agent. It has the property to absorb moisture.... View Article

An aqueous solution turns red litmus solution blue. Excess addition of which of the following solution would reverse the change? (a) Baking powder (b) Lime (c) Ammonium hydroxide solution (d) Hydrochloric acid

Answer: (d) Hydrochloric acid If the solution turns red litmus to blue colour then the solution should be basic in... View Article

What happens when a solution of an acid is mixed with a solution of a base in a test tube? (i) The temperature of the solution increases (ii) The temperature of the solution decreases (iii) The temperature of the solution remains the same (iv) Salt formation takes place (a) (i) only (b) (i) and (iii) (c) (ii) and (iii) (d) (i) and (iv)

Answer: (d) (i) and (iv) When acid is mixed with a solution of base it results in a neutralization reaction.... View Article

You are provided with two containers made up of copper and aluminium. You are also provided with solutions of dilute HCl, dilute HNO₃, ZnCl₂ and H₂O. In which of the above containers these solutions can be kept?

Answer: These solutions can be kept in a copper container because copper is a noble metal which will not react... View Article

On adding a drop of barium chloride solution to an aqueous solution of sodium sulphite, a white precipitate is obtained. (a) Write a balanced chemical equation of the reaction involved (b) What other names can be given to this precipitation reaction? (c) On adding dilute hydrochloric acid to the reaction mixture, white precipitate disappears. Why?

Answer: (a) On adding a drop of Barium Chloride solution to an aqueous solution of sodium sulphite, barium sulphite is... View Article

What happens when zinc granules are treated with a dilute solution of H2SO4, HCl, HNO3, NaCl and NaOH, also write the chemical equations if a reaction occurs.

Answer: When Zinc granules react with dil H2SO4 displacement reaction takes place leading to the formation of ZnSO4 liberating H2... View Article

What happens when a piece of silver metal is added to copper sulphate solution? Also, write the balanced chemical equation if the reaction occurs

Answer: When silver metal is added to copper sulphate solution there will not be any reaction as silver is non-reactive... View Article

What happens when a piece of aluminium metal is added to dilute hydrochloric acid? Also, write the balanced chemical equation if the reaction occurs

Answer: Aluminum reacts with diluted hydrochloric acid at room temperature. The metal aluminium dissolves in hydrochloric acid, producing aluminum chloride... View Article

What happens when a piece of zinc metal is added to copper sulphate solution? Also, write the balanced chemical equation if the reaction occurs

Answer: When zinc is added to copper sulphate (CuSO4) solution due to more reactivity of zinc, cooper is replaced by... View Article

Give the characteristic tests for the following gases (a) CO2 (b) SO2 (c) O2 (d) H2

Answer: (a) CO2 Limewater is basically a solution of calcium hydroxide. So if we bubble carbon dioxide through the solution... View Article

«
1
…
1,390
1,391
1,392
1,393
1,394
…
5,472
»