# NCERT Solutions for Class 10 Science Chapter 2 Acids, Bases, and Salts

NCERT Solutions for Class 10 Science Chapter 2 Acids, Bases, and Salts: In every student's life, class 10 is a very important stage. The result of your class 10 board exam will give you the right direction towards your career. As per the previous year's paper analysis, there is a higher probability of 3 marks or 5 marks questions appearing in the exam from chapter 2 Acid, Bases and Salts. If you want to score well in your board exams then solutions for NCERT class 10 science chapter 2 Acids, Bases and Salts will give you proper knowledge of the concepts, equations, and formulas. In this article, you will get CBSE NCERT solutions for class 10 science chapter 2 acids, bases, and salts. With the help of NCERT solutions , you can easily solve questions . If you want to score well in other subjects, you are advised to go through the NCERT solutions

Available Now: NCERT free solutions for class 10 science

Available Now: NCERT textbook solutions for class 10

What you are going to learn in NCERT solutions for class 10 science chapter 2 Acids, Bases, and Salts?

• In Chapter 2 Acids, Bases and Salts, you will also study when an acid reacts with a metal, hydrogen gas is evolved and a corresponding salt is formed.
• Through this chapter, you will get to know that the strength of an acid or an alkali can be tested by using a scale called the pH scale (0-14).
• A salt is formed when a base reacts with metal, along with the evolution of hydrogen gas which has a negative ion composed of the metal and oxygen.
• When an acid reacts with a metal hydrogen carbonate or metal carbonate, it gives the corresponding salt, water, and carbon dioxide gas.
• Electricity in water is conducted by Acidic and basic solutions because they produce hydrogen and hydroxide ions respectively.
• in everyday life and in industries, salts have various uses.

CBSE NCERT solutions for class 10 science chapter 2 Acids, Bases, and Salts

Litmus is a common indicator that is used to identify acid and base. The color of litmus paper turns to blue indicates that the chemical is a base. If there is no change in color, then the chemical is either acidic or neutral.

First marks the three test tubes as A, B, and C.

Now,

(i) First of all, put the red litmus paper in each test tube one by one. The test tube in which red litmus paper will turn blue indicates the solution of that test tube is basic/Alkaline in nature.

(ii) Now remaining two are either acidic or neutral. Now mix a drop of the basic solution with a drop of each of the remaining two solutions separately and then the nature of the drops of the mixtures is checked. If the colour of the red litmus turns blue, then the second solution is neutral and if there is no change in colour, then the second solution is acidic. This is because acidic and basic solutions neutralize each other.

## NCERT solutions for class 10 science chapter 2 Acids, Bases and Salts

Topic 1.2 - Understanding the chemical properties of acids and bases

Curd and sour substances not be kept in brass and copper vessels because curd and other sour substances contain acids.

Therefore, when they are kept in brass and copper vessels, the metal reacts with the acid to liberate hydrogen gas and harmful products, thereby may spoil the food.

Hydrogen gas is usually liberated when an acid reacts with a metal.

When zinc granules react with dilute sulphuric acid, then the bubbles of the soap solution are formed. These soap bubbles contain hydrogen gas and a zinc sulphate solution is formed.

$Zn +2 H_2SO_4\Rightarrow Zn(SO_4)_2+2H_2$

The evolved hydrogen gas can be tested by taking a burning candle near a soap solution containing hydrogen gas. If the candle burns with a pop sound, it confirms the evolution of hydrogen gas.

During the chemical reaction, the evolved gas extinguishes a burning candle which means the gas is carbon dioxide.

Since, one of the compounds formed during this reaction is calcium chloride and carbon dioxide is formed when dilute hydrochloric acid reacts with a metal carbonate (or metal hydrogen carbonate) producing effervescence it means the metal compound is calcium carbonate (It cannot be calcium hydrogen carbonate because calcium hydrogen carbonate is found only in solution, it is also unstable to exist as a solid). Hence, the compound A is calcium carbonate.

The chemical reaction is written as follows:

$CaCO_3+2HCL_{(aq)}\rightarrow CaCL_{2(aq)}+CO_{2(g)}+H_2O_{(l)}$

## NCERT solutions for class 10 science chapter 2 Acids, Bases, and Salts

Topic 2.2 What do all acids and all bases have in common?

Acids form hydrogen ions [$H^+$ (aq) ions] in its aqueous solution which is responsible for their acidic characters. $HCl \ and \ HNO_3$  form hydrogen ions in aqueous solution hence, they show acidic characters in aqueous solution.

The reaction of HCL is as follows:
$HCl_{(aq)}\rightarrow H^++Cl^-$
$H^++H_2O\rightarrow H_3O^+$

While solutions of compounds like alcohol and glucose do not form hydrogen ions in the solution, hence, they do not show acidic character.

Acids dissociate in aqueous solutions to form ions. Like hydrogen ions ($H^+$) or hydronium ions ($H_3O^+$)  and the presence of these ions in an aqueous solution of acid are responsible for conducting electricity.

The colour of litmus paper changes only in the presence of ions like hydrogen ($H^+$) or hydronium ($H_3O^+$) ions. Dry HCl does not contain  ($H^+$) or ($H_3O^+$) ions. It can produce these ions only in the form of an aqueous solution.

Hence, because of that dry HCl gas does not change the colour of dry litmus paper.

The process of dissolving an acid in water is highly exothermic in which a large amount of heat is evolved. It is always recommended that acid should slowly be added to water because evolved heat is easily absorbed by a large amount of water.

If it is done the other way, then it is possible that because of the large amount of heat generated, the mixture splashes out and causes burns,

When the solution of an acid is diluted, the concentration of hydronium ions $(H_3O^+)$ per unit volume decreases.

That means, the strength of the acid decreases.

The concentration of hydroxide ions $\left (OH^{-} \right )$  would increase when excess base is dissolved in a solution of sodium hydroxide.

## NCERT solutions for class 10 science chapter 2 Acids, Bases, and Salts

Topic 2.3 How strong are acid or base solutions

The pH value of less than 7 indicates an acidic solution while greater than 7 indicates a basic solution. The pH value of a neutral solution is 7. And the acidic solution has more hydrogen ion concentration.

Therefore, solution A with pH = 6  is acidic and has more hydrogen ion concentration than solution B with pH = 8 which is basic.

Concentration of  $H^+$ (aq) can have a varied effect on the nature of the solution.When we increase the concentration of $H^+$ ions in the solution, the solution becomes more acidic, while when we decrease the concentration of $H^+$ ions in the solution, the basicity of the solution increases.

Yes, the basic solution also has H+(aq) ions. However, they are basic because the concentration of hydrogen ions in them is less as compared to the concentration of hydroxide ions $[OH^- ions]$ that makes the solution basic.

Quicklime, slaked lime and chalk are basic in nature. When they react with acids, the neutralization reaction takes place.

Therefore, If the soil is acidic and improper for cultivation, then to increase the basicity of soil, the farmer would treat the soil with quicklime or slaked lime or chalk

## NCERT solutions for class 10 science chapter 2 Acids, Bases, and Salts

The common name of the compound  $CaOCl_{2}$  is bleaching powder.

Calcium hydroxide  $[Ca(OH)_2]$  on treatment with chlorine yields bleaching powder.

Washing soda  $(Na_2CO_3.10H_20)$ is used for softening hard water.

When a solution of sodium hydrogen carbonate (sodium hydrogen carbonate) is heated, it undergoes decomposition reaction to form sodium carbonate and water, and carbon dioxide gas is liberated.

The equation of the reaction involved is:

$2NaHCO_3 \xrightarrow[]{heat} Na_2CO_3+H_2O+CO_2$

The chemical equation for the reaction of Plaster of Paris and water can be represented as $CaSO_4.\frac{1}{2}H_2O+ 1\frac{1}{2}H_2O\rightarrow CaSO_4.2H_2O$

## NCERT solutions for class 10 science chapter 2 Acids, Bases, and Salts Excercise:

(a) 1    (b) 4    (c) 5   (d) 10

(d) As we have lean bases turn red litmus blue. The basic solution has a pH value of more than 7. Since the solution turns red litmus blue, therefore its pH is likely to be > 7 i.e. 10.

(a) NaCl           (b) HCl           (c) LiCl           (d) KCl

(b) The solution contains HCI reacts with crushed egg-shells to give a gas that turns lime-water milky.

(a) 4 mL          (b) 8 mL          (c) 12 mL          (d) 16 mL

It is given that
10ml of NaOH neutralizes 8ml Solution of HCl
$\therefore$ 1 ml of NaOH neutralizes = $\frac{8}{10} = \frac{4}{5} \ ml$ Solution of HCl
Therefore, 20 ml of NaOH will neutralise= $\frac{4}{5}\times 20=16 \ ml$ solution of HCL

Therefore, 16 ml of HCl solution will be required to neutralize the 20 ml of NaOH.

(a) Antibiotic

(b) Analgesic

(c) Antacid

(d) Antiseptic

(c) The antacid is used for treating indigestion.

(a) dilute sulphuric acid reacts with zinc granules.

(b) dilute hydrochloric acid reacts with magnesium ribbon.

(c) dilute sulphuric acid reacts with aluminum powder.

(d) dilute hydrochloric acid reacts with iron filings.

Balanced equations are:-

(a) $H_2SO_4_{(aq)}+Zn_{(s)}\rightarrow ZnSO_4_{(aq)}+H_2_{(g)}$

(b) $2HCl_ {(aq)} + Mg_{(s)}\rightarrow MgCl_{2 (aq)} + H_{2(g)}$

(c) $3H_2SO_{4 (aq)} + 2Al_{ (s)} \rightarrow Al_2(SO_4)_{3 (aq)} + 3H_{2 (g)}$

(d) $6HCl_ {(aq)} +2Fe_{ (s)} \rightarrow 2FeCl_{3(aq)} +3H_{2(g)}$

Take the solution of dilute hydrochloric solution and glucose. Two nails are fitted on a cork and are kept it in a 100 mL beaker. The nails are then connected to the two terminals of a 6-volt battery through a bulb and a switch.  Dilute HCl is poured in the beaker and current is switched on. Now, the same experiment is performed with a glucose solution and an alcohol solution.

We will observe that the bulb glows in the HCl solution and does not glow in the glucose solution.

Because: HCl dissociate into H + (aq) and Cl -(aq) ions. These ions conduct electricity in the solution resulting in the glowing of the bulb.  On the other hand, the glucose solution does not dissociate into ions. Therefore, it does not conduct electricity.

Conclusion:
From this activity, it can be concluded that all acids contain hydrogen but not all compounds containing hydrogen are acids. That is why, though compounds like alcohols and glucose contain hydrogen, they are not categorized as acids.

Distilled water is a pure form of water that does not contain ions. Therefore, it does not conduct electricity. Rainwater on the other hand, being an impure form of water, contains many ionic compounds such as acids and therefore it conducts electricity.

Acids do not show acidic behavior in the absence of water because acids form hydrogen ions [H+ (aq) ions] in its aqueous solution which are responsible for their acidic characters and the dissociation of hydrogen ions from an acid occurs in the presence of water only.

Therefore in the absence of water, acids do not produce hydrogen ions and hence do not show acidic behavior.

Solution with pH equal tois a neutral solution. Therefore, a neutral solution is D

The solution with the highest pH is strongly alkaline. Therefore, a strongly alkaline solution is with a pH equal to 11

The solution with the lowest pH value is strongly acidic. Therefore, a strongly acidic solution is B with  pH equal to 1

Solution with pH less than 7 but close to 7 is weakly acidic. Therefore, the weakly acidic solution is with a pH equal to 4

The solution with a pH greater than 7 but close to 7 is weakly alkaline. Therefore, a weakly alkaline solution is E with pH equal to 9

When an acid reacts with magnesium metal, hydrogen gas is produced which causes fizzing. Stronger acids having a greater number of hydrogen ions in it. Hence, fizzing will occur strongly in test tube A, in which hydrochloric acid (HCI) is added.

This is because HCI is a stronger acid as compared to $\left (CH_{3}COOH \right )$ and therefore, during the chemical reaction with magnesium metal, HCl will produce more hydrogen gas due to which fizzing will be more vigorous in test-tube A.

The pH of fresh milk is 6.

As milk turns into curd, lactic acid is formed due to which it becomes more acidic. Therefore, the pH of milk will decrease.

(a)     Why does he shift the pH of the fresh milk from 6 to slightly alkaline?

Fresh milk is slightly acidic in nature, The milkman shifts the pH of the fresh milk from 6 to slightly alkaline by adding little baking soda.

Because this will prevent the milk from getting sour due to lactic acid formation.

(b)       Why does this milk take a long time to set as curd?

Since this milk is slightly basic than usual milk, the lactic acid, formed during curdling, needs to first neutralize the alkali present in the milk.

Therefore, it takes a longer time for the curd to set.

Plaster of Paris should be stored in a moisture-proof container because it absorbs moisture (or water) to form a hard substance called gypsum which makes Plaster of Paris useless.

$CaSO_4.\frac{1}{2}H_2O+1\frac{1}{2}H_2O\rightarrow CaSO_4.2H_2O$

A reaction in which an acid and base react with each other to give a salt and water is known as neutralization reaction. That is:

$Acid + Base \rightarrow Salt + Water$

For example:

(i) Sodium hydroxide (NaOH) reacts with hydrochloric acid (HCl) to form sodium chloride (NaCl) and water:

$NaOH + HCl \rightarrow NaCl + H_2O$

(ii) Magnesium hydroxide reacts with hydrochloric acid to form magnesium chloride and water:

$Mg(OH)_2+2HCl \rightarrow MgCl_2+2H_2O$

Uses of Washing Soda:

(i) It is used for removing the permanent hardness of the water.

(ii) It is used in glass, soap, and paper industries.

Uses of Baking Soda:

(i) It is used in soda-acid fire extinguishers.

(ii) It is used in making baking powder. Baking powder is a mixture of baking soda and a mild edible acid called tartaric acid. When baking powder is heated or mixed in water, it releases $CO_2$ that makes cakes or bread fluffy.

## NCERT Solutions for Class 10 Science - Chapter wise

 Chapter No. Chapter Name Chapter 1 NCERT textbook solutions for class 10 science chapter 1 Chemical Reactions and Equations Chapter 2 CBSE NCERT solutions for class 10 science chapter 2 Acids, Bases, and Salts Chapter 3 NCERT free solutions for class 10 science chapter 3 Metals and Non-metals Chapter 4 Solutions for NCERT class 10 science chapter 4 Carbon and Its Compounds Chapter 5 NCERT textbook solutions for class 10 science chapter 5 Periodic Classification of Elements Chapter 6 CBSE NCERT solutions for class 10 science chapter 6 Life Processes Chapter 7 NCERT textbook solutions for class 10 science chapter 7 Control and Coordination Chapter 8 Solutions for NCERT class 10 science chapter 8 How do Organisms Reproduce? Chapter 9 NCERT free solutions for class 10 science chapter 9 Heredity and Evolution Chapter 10 CBSE NCERT solutions for class 10 science chapter 10 Light Reflection and Refraction Chapter 11 Solutions for NCERT class 10 science chapter 11 The Human Eye and The Colorful World Chapter 12 NCERT free solutions for class 10 science chapter 12 Electricity Chapter 13 NCERT textbook solutions for class 10 chapter 13 Magnetic Effects of Electric Current Chapter 14 NCERT solutions for class 10 science chapter 14 Sources of Energy Chapter 15 Solutions for NCERT class 10 science chapter 15 Our Environment Chapter 16 NCERT solutions for class 10 science chapter 16 Sustainable Management of Natural Resources

## Benefits of NCERT solutions for class 10 science chapter 2 Acids, Bases, and Salts

• You can use these NCERT solutions like a time savior, here you will get solutions for all the exercises and extra questions related to this chapter.
• All the solutions are created by experienced experts.
• The language of the solutions is easy to understand.
• The NCERT solutions for class 10 science chapter 2 Acids, Bases, and Salts, helps you to clear your concepts.
• Along with the class 10 science subjects, you will also get solutions for NCERT class 10 maths.