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 :

Which of the following aqueous solution reacts with crushed egg-shells to give a gas that turns lime water milky ?

(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?

Read the following passage and answer the questions that follow :
Salts are formed by reactions of acids and bases. Strong acids react with strong bases to form neutral salts. Weak acids react with strong bases to form basic salts. Acidic salts are formed by strong acids and weak bases. $\ce{Na2CO3}$ and $\ce{NaHCO3}$ are salts of strong base ($\ce{NaOH}$) and weak acid ($\ce{H2CO3}$). Bleaching powder is prepared when slaked lime reacts with dry chlorine gas. Crystalline salts are hydrated and lose water on heating. Gypsum on heating at $373\ \text{K}$ gives Plaster of Paris.
(a) What is the formula of POP (Plaster of Paris) ? What is its chemical name?
(b) Name the compound of sodium which is used for softening hard water. What is its chemical formula ?
(c) (i) (I) What is water of crystallization ?
(II) Write the preparation of bleaching powder.
OR
(c) (ii) (I) Name an indicator used by visually impaired children.
(II) Give one use of bleaching powder.

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 :

Which of the following statements is true for acids ?

Assertion (A): Sodium acetate is a basic salt.
Reason (R): It is because it is a salt of weak acid and strong base.

Which of the following solution will not conduct electricity ?

Read the following passage and answer the questions that follow:
Various substances can be classified as acids, bases and salts. Based on their strength, acids and bases are further classified as strong and weak. We can find this by using universal indicators, which shows different colours at different concentrations of hydrogen ions in a solution. A pH scale has been developed, which indicates acidic or basic nature of a solution, from 0 (very acidic) to 14 (very alkaline).
(i) Define universal indicator.

Read the following passage and answer the questions that follow:
Various substances can be classified as acids, bases and salts. Based on their strength, acids and bases are further classified as strong and weak. We can find this by using universal indicators, which shows different colours at different concentrations of hydrogen ions in a solution. A pH scale has been developed, which indicates acidic or basic nature of a solution, from 0 (very acidic) to 14 (very alkaline).
(ii) The pH of solution 'A' is 6 and the pH of solution 'B' is 10. Which solution has more hydrogen ion concentration ?

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.

Give reasons for the following :
(a) Why do acids not show acidic behaviour in the absence of water ?
(b) Why should curd and sour substances not be kept in copper vessels ?

Answer the following :
(a) Why does distilled water not conduct electricity, whereas rainwater does ?
(b) While diluting an acid, why is it recommended that the acid should be added to water and not water to acid ?

Read the following passage and answer the questions that follow:
Various substances can be classified as acids, bases and salts. Based on their strength, acids and bases are further classified as strong and weak. We can find this by using universal indicators, which shows different colours at different concentrations of hydrogen ions in a solution. A pH scale has been developed, which indicates acidic or basic nature of a solution, from 0 (very acidic) to 14 (very alkaline).
(iii) (b) Four solutions A, B, C and D when tested with universal indicator showed pH as 5, 1, 9 and 13 respectively. Which solution is : (I) strongly alkaline, and (II) strongly acidic ?

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 ?

Turmeric is an example of :

'Phenolphthalein' is an example of :

Which of the following acid-base indicators will be used by a visually challenged student to detect the presence of acid in a given solution ?

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 :

(A) Name the acid present in ant sting and give its chemical formula. Give the common method to get relief from the pain and irritation caused by ant sting.
(B) Two solutions 'X' and 'Y' have pH values 3.0 and 9.5 respectively.
Which of these will turn blue litmus to red and which will turn phenolphthalein from colourless to pink ?

The acid present in tamarind 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'.

Which of the following compound is formed when electric current is passed through brine solution?

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 ?

Which of the following compounds is used as both an antacid and in a fire extinguisher ?

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 ?

A substance 'X', commonly used in baking products, reacts with dilute $\ce{HCl}$ to produce a gas 'Y' which is used in one type of fire extinguisher. Name the substance 'X' and gas 'Y'. Write a balanced chemical equation for the reaction which takes place.

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?

Which of the following salts do not contain water of crystallization ?
(i) Bleaching powder
(ii) Baking soda
(iii) Gypsum
(iv) Washing soda

Which of the following compound is formed when $\ce{CO2}$ gas is passed through ammoniacal brine solution?

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.