Class 10 NCERT Solutions Acids Bases and Salts (2)

Scroll down for PDF

Class 10 NCERT Solutions Acids Bases and Salts (2)- NCERT Solutions prepared for CBSE students by the best teachers in Delhi.

Class X Chapter 2 – Acids Bases and Salts Science

Page 1 of 14

Question 1: You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?

Answer: If the colour of red litmus paper gets changed to blue, then it is a base and if there is no colour change, then it is either acidic or neutral. Thus, basic solution can be easily identified.

Let us mark the three test tubes as A, B, and C. A drop of the solution in A is put on the red litmus paper. Same is repeated with solution B and C. If either of them changes colour to blue, then it is basic. Therefore, out of three, one is eliminated. Out of the remaining two, any one can be acidic or neutral. Now a drop of basic solution is mixed 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 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. Hence, we can distinguish between the three types of solutions.

Why should curd and sour substances not be kept in brass and copper vessels?

Answer

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 spoiling the food.

Question 2:

Which gas is usually liberated when an acid reacts with a metal? Illustrate with anexample. How will you test for the presence of this gas?

Answer

Hydrogen gas is usually liberated when an acid reacts with a metal. Take few pieces of zinc granules and add 5 ml of dilute H2SO4. Shake it and pass the gas produced into a soap solution. The bubbles of the soap solution are formed. These soap bubbles contain hydrogen gas. 

We can test the evolved hydrogen gas by its burning with a pop sound when a candle is brought near the soap bubbles.

Question 3:

Metal compound A reacts with dilute hydrochloric acid to produce effervescence. The gas evolved extinguishes a burning candle. Write a balanced chemical equation for the reaction if one of the compounds formed is calcium chloride.

Answer

Why do HCl, HNO3, etc., show acidic characters in aqueous solutions while solutions of compounds like alcohol and glucose do not show acidic character?

Answer

The dissociation of HCl or HNO3 to form hydrogen ions always occurs in the presence of water. Hydrogen ions (H+) combine with H2O to form hydronium ions (H3O+).

The reaction is as follows:

Although aqueous solutions of glucose and alcohol contain hydrogen, these cannot dissociate in water to form hydrogen ions. Hence, they do not show acidic character.

Question 2:

Why does an aqueous solution of an acid conduct electricity?

Answer

Acids dissociate in aqueous solutions to form ions. These ions are responsible for conduction of electricity.

Question 3:

Why does dry HCl gas not change the colour of the dry litmus paper?

Answer

Colour of the litmus paper is changed by the hydrogen ions. Dry HCl gas does not contain H+ ions. It is only in the aqueous solution that an acid dissociates to give ions. Since in this case, neither HCl is in the aqueous form nor the litmus paper is wet, therefore, the colour of the litmus paper does not change.

Question 4:

While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?

Answer

Since the process of dissolving an acid in water is exothermic, it is always recommended that acid should be added to 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.

Question 5:

How is the concentration of hydronium ions (H3O+) affected when a solution of an acid is diluted?

Answer

When an acid is diluted, the concentration of hydronium ions (H3O+) per unit volume decreases. This means that the strength of the acid decreases.

Question 6:

How is the concentration of hydroxide ions (OH−) affected when excess base is dissolved in a solution of sodium hydroxide?

Answer

The concentration of hydroxide ions (OH−) would increase when excess base is dissolved in a solution of sodium hydroxide.


Students should free download the NCERT solutions and get better marks in exams. Studiestoday.com panel of teachers recommend students to practice questions in NCERT books and download NCERT solutions.

Tags: 


Click on the text For more study material for Science please click here - Science

Latest NCERT & CBSE News

Read the latest news and announcements from NCERT and CBSE below. Important updates relating to your studies which will help you to keep yourself updated with latest happenings in school level education. Keep yourself updated with all latest news and also read articles from teachers which will help you to improve your studies, increase motivation level and promote faster learning

JEE in Punjabi too after English, Hindi and Gujarati

Punjab Minister Tript Rajinder Singh Bajwa requested the joint technology entrance exam (main) to be conducted in Punjabi and other regional languages too. In his letter to Union HRD Minister Ramesh Pokhriyal Nishank, the Punjab Minister for Higher Education and...

Simple tips to Excel in Examinations

We are entering the last quarter of the Academic Session. With examinations just around the corner, I am sure all of us are carrying a mixed bag of Stress, Excitement, and Anxieties!! So, first and foremost- Let’s be Positive and Futuristic! It’s most important to...

Requirements for admissions in CBSE affiliated Schools

CBSE gives an advanced form of education. They try to indulge students in interactions and teach application based subjects along with some others. Due to this preponderance of parents, they tend to admit their children in CBSE affiliated schools. General conditions...

CBSE examination board hike the fee for class 10th and 12th

The CBSE (Central Board Secondary Education) increased the examination fees for classes 10 and 12 of the 2020 boards, with no profit no loss principle, from Rs. 750 to Rs 1500, for all categories of students, including SC/ST candidates for all schools throughout India...

TIPS: Study habits for success

Being a student is fairly a difficult job. Alongside maintaining your curricular as well as extra-curricular activities adds more to it. Performance in academics is one of the major concerns. Every parent now tries to get their children more indulged in studies. Need...

×
Studies Today