WORKSHEET ON ACID, BASE AND SALT

Section: Exposition
Each question carries 1 mark:

1. State whether the following statements are true or false. Rewrite the false statement
correctly
(a) Neutral solution have pH of 0
(b) Solution of sodium hydrogen carbonate is acidic in nature.
(c) Correct increasing order of the acidic strength is: Water < Acetic acid< Hydrogen
chloride
(d) The colourless gas B is produced when egg shell is treated with a solution A. The
gas B turns lime water milky. A=HCl and B=CO2

2. Fill in the blanks:
(a) An indicator changes its _______ with change of the nature of the solution.
(b) An acid produces ______ ion in aqueous solution.
(c) The properties of ______ are due to the hydrogen ion it produces in aqueous
solution.
(d) A water soluble base produces _____ ions in solutions.
(e) The reaction between an acid and base is called _____ reaction.
(f) The concentration of H+ ion given by HCl is _____ than that given by equal
concentration of CH3COOH.

3. Which oxides are acidic and which oxides are basic?

4. How can you test that metallic oxides are basic while non -metallic oxides are acidic?

5. Name one oxide which is both acidic as well as basic .What are these oxides called?

6. Two solutions A and B have pH values of 3.0 and 9.5 respectively. Which of these will turn
litmus solution from blue to red and which will turn phenolphthalein from colorless to pink?

7. Ishaan prepared China rose indicator by keeping the petals of the flower in hot water for
some time. He used the coloured solution for testing three solutions A,B and C. Solution A
turns to dark pink, solution B remains light pink and solution C turns to green. Mark the
correct

Solution A                                               Solution B                              Solution C                                 


Lemon juice                                         Sugar solution                             Milk of magnesia

lemon juice                                          Orange juice                                    Sugar solution                      
                                     
Orange juice                                         Vinegar                                       Salt solution                              

8. Ravi Shankar took a small amount of sulphur in deflagrating spoon and heated it over a burner. As soon as it started burning he put it in a gas jar and covered it with a lid. After sulphur stopped burning he added a small amount of water in it and dissolved the gas in water by shaking it. He then tested the solution with red and blue litmus paper. What did he observe?

(a) In the solution the blue litmus paper turned red.
(b) In the solution the red litmus paper turned blue.
(c) There was no change in the colour of litmus paper.
(d) Blue litmus paper turned red and red litmus paper turned blue.

Each question carries 2 marks:

9. Complete the following ionization reactions:
(a) HCl (aq) →
(b) H2SO4 (aq)→
(c) HNO3 (aq) →
(d) NaOH(aq) →

10. Write balanced chemical equations for the following word equations:
(a) Reaction of an acid with metal
Calcium + Hydrochloric Acid → Calcium chloride + Hydrogen
(b) Reaction of a base with metal
Zinc + Sodium Hydroxide → Sodium zincate + Hydrogen
(c) Reaction of an acid with metal carbonate/ metal hydrogen carbonate
Calcium carbonate + Hydrochloric acid → Calcium chloride + Carbon dioxide
+ Water
(d) Reaction of an acid with metallic oxides
Magnesium oxide + Hydrochloric acid → Magnesium Chloride + Water

11.A student dropped few pieces of calcium carbonate in dilute hydrochloric acid, contained in a test tube. The carbon dioxide gas evolved was then passed through lime water(calcium hydroxide)and it turned milky due to the formation of insoluble calcium carbonate. Write the balanced chemical equations for all the changes observed

12. Litmus paper is used as an indicator to check whether a solution is acidic or basic. When red litmus is dipped in a basic solution, it turns blue and when blue litmus paper is dipped in an acidic solution, it turns red. If you were given a strip of blue litmus paper, which pair of substances would help you turn it red?

(a) Soap solution and bleach

(b) Ammonia and egg white

(c) Egg yolk and black coffee

(d) Distilled water and sea water

Each question carries 2 marks:

 13. Observe the following activity and answer the questions that follow:

(a) What do you observe in boiling test tube ‘A’
(b) Write the balanced chemical equation for the reaction taking place in test tube ‘ A’
(c) What do you observe when the colourless gas is passed through solution of calcium hydroxide? Also write the relevant equation
(d) What will happen if sodium carbonate is replaced by sodium hydroxide solution in test tube ‘A’?

14. Study the following pH chart and answer the questions that follows:



Each question carries 3 marks

 Study the following chart and answer the questions that follows:
(a) Which solution has more hydrogen ion concentration?
(b) The pH values of three acids A,B, C having hydrogen ion concentration are 1x10-5 , 1x10-2 and 1x103 respectively. Arrange these acids in order of increasing acid strength

(c) 1.0 mL of lemon juice was taken in a test tube. Its pH was determined by using a
pH paper. Excess of NaOH solution was then added to the lemon juice and the pH
of the resulting solution was again determined It was observed that the color of the
pH paper changed from _____________ to ___________________ .

(d) The pH of soil A is 7.0 and that of soil B is 4.0.Which of these should be treated
with Ca(OH)2 and why?


Each question carries 3 marks:


 Interpretation & Reasoning
Each question carries 1 mark:

18. What will you observe when dilute hydrochloric acid is added to a small amount of copper oxide in a beaker?
19. Aqueous solution of HCl shows acidic character. But the aqueous solution of glucose fails to do so. Why?
Compound ‘X’
+ Zn → ‘A’ +H2(g)
+ HCl → ‘B’ +H2O
+ CH3COOH → ‘C’ +H2O

Each question carries 2 marks:

20. A white solid when dropped in water produces a hissing sound. What may the solid be? Give a chemical reaction for the above. Name the product formed.

21. An element ‘X’ on reaction with a dilute acid evolves a gas that burns with a pop sound, while a compound ‘Y’ on reaction with dilute acid evolves a gas that turns lime water milky. Identify X and Y.
22.
22. What is the basicity of phosphoric acid and hydrochloric acid? What is the role of the acid in our stomach?

Each question carries 3 marks:

23. Taj Mahal is getting spoiled due to acid rain. The gases present in atmosphere are SO2, SO3 and NO2. Which acids will react with Taj Mahal ? Explain with the help of chemical reactions.
24. Name the chemicals used in the Soda acid Fire extinguisher and the gas evolved from it when used? Why is NaHCO3 used in soda-acid fire extinguishers?
Section: Problem Solving
25. When a metal X is treated with cold water, it gives a basic salt Y with molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y, Z.