Acids, Bases and Salts — Class 10 Science PYQs

A metal carbonate reacts with a solution X which forms a salt, water and a gas Y. What are X and Y?

Tamarind is a natural source of which acid ?

To a small amount of copper oxide in a beaker, when we add dilute hydrochloric acid slowly with stirring, the change in the colour of the solution is due to the formation of :

When zinc reacts with $\ce{NaOH}$, the product formed is :

An aqueous solution turns red litmus blue. Excess addition of which of the following solution would reverse the change ?

How will you protect yourself from the heat generated while diluting a concentrated acid ?

Study the following table and select the correct option :
begin{tabular}{|c|c|c|c|c|}
hline & Salt & Acid used & Base used & Nature of Salt
hline

When ethanoic acid is treated with sodium hydrogen carbonate, the gas evolved is :

(a) What are amphoteric oxides ?
(b) Categorise the following based on their nature : $\ce{ZnO}$, $\ce{Na2O}$, $\ce{CO2}$

Why does one feels pain and irritation when stung by honey-bee ? Rubbing of baking soda on the stung area gives relief. How?

Four solutions, namely fructose, ethanol, hydrochloric acid and sodium hydroxide filled in four separate beakers are connected one by one in an electric circuit with a bulb. The solutions in which the bulb will glow when current is passed are :

Give reasons for the following :
(a) Dry $\ce{HCl}$ gas does not change the colour of a dry blue litmus paper.
(b) Copper sulphate crystals turn white on heating.

Attempt either (a) or (b) :
(a) Give reasons :
(i) For dilution of an acid, acid is added into water and not water into acid.
(ii) Dry $\ce{HCl}$ gas does not turn blue litmus red whereas dilute $\ce{hydrochloric}$ $\ce{acid}$ does.
(iii) Blue colour of $\ce{Copper(II)}$ $\ce{sulphate}$ crystals turns white on heating.

Which one of the following can be used as an acid-base indicator by a visually impaired (blind) student ?

How is a universal indicator obtained ? How is the wide range of pH of solution tested by it ?

The pH of the gastric juices released during digestion is :

Rain water is called ‘acid rain' when its :

Tomato is a natural source of which acid?

The acid presents in nettle sting is :

How is tooth decay related to $\text{pH}$ ? How can it be prevented ?

The pH plays an important role in our daily life. Strength of acids and bases depends on the number of $\ce{H+}$ ions and $\ce{OH-}$ ions produced by these respectively. pH scale helps in predicting the strength of acids and bases by measuring hydrogen ion concentration in a solution.
Answer the following :
(a) What type of indicator is used to predict how strong an acid or base is ?
(b) Three solutions A, B and C showed pH as 3, 5 and 7. Which solution has the highest concentration of $\ce{H+}$ ions ?
(c) What are strong acids and weak acids ?
OR
(c) (i) Under what condition is rainwater called acid rain ?
(ii) In the following acids, identify weak acids :
Nitric acid, hydrochloric acid, acetic acid, sulphuric acid, formic acid.

Write the balanced chemical equation for the formation of substance 'Z'.

Identify the substance 'A' and write the balanced chemical equation of the reaction which takes place in its preparation.

Write the balanced chemical equations involved in the preparation of
(a) Bleaching powder
(b) Baking soda

Write the balanced chemical equation for the preparation of :
(a) Sodium hydroxide by electrolysis of brine solution
(b) Sodium carbonate

Explain chlor-alkali process with chemical equation. Name the products formed at anode and cathode.

Attempt either (a) or (b) :
OR
(b) Write the preparation of the following compounds with balanced chemical equation :
(i) $\ce{NaOH}$ by chlor-alkali process
(ii) Baking Soda
(iii) Plaster of Paris

Attempt either subpart (a) or (b) :
(a) During electrolysis of brine solution, a gas (A) is liberated at the anode. When the gas (A) is passed through slaked lime, a compound (B) is formed which is used for disinfecting drinking water.
(i) Write the names of (A) and (B).
(ii) Write the chemical equation involved.
(iii) Write one use of compound (B) other than disinfecting water.

Baking powder is a mixture of :

Which one of the following chemicals is used in soda-acid fire-extinguishers ?

What happens :
(I) If a drop of red litmus solution is added to the aqueous solution of substance 'Z'?
(II) If $\ce{CO2}$ gas is passed through ammoniacal solution of aqueous $\ce{NaCl}$ ?

Write the preparation of Baking soda. How does it help in making cakes soft and spongy ?

Write the preparation of following compounds with balanced chemical equation :
(i) Baking soda
(ii) Bleaching powder
(iii) Plaster of Paris

(a) Name the acid present in ant’s sting.
(b) Give reason :
(i) While diluting an acid, it is recommended that the acid should be added to water.
(ii) Baking soda is used as an antacid.

Which of the following compounds is used for removing permanent hardness of water?

Define the following terms :
(i) Olfactory indicator
(ii) Water of crystallization

Attempt either subpart (a) or (b) :
OR
(b) Define the following terms with an example :
(i) Olfactory indicators
(ii) Water of crystallisation
(iii) Basic salt

(a) A compound ‘A’ is used in soda-lime fire-extinguisher and decomposes on heating to form compound ‘B’. Compound ‘B’ is used for removing permanent hardness of water. Identify ‘A’ and ‘B’.
(b) Write chemical formula of Plaster of Paris. At what temperature gypsum is heated to obtain Plaster of Paris ?

(a) Give the chemical name and formula of Plaster of Paris.
(b) Write the chemical equation of its preparation.
(c) Give any two uses of it.