CBSE Class 10 Science Acids Bases and Salts Assignment Set B

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Assignment for Class 10 Science Chapter 2 Acids Bases Salts

Class 10 Science students should refer to the following printable assignment in Pdf for Chapter 2 Acids Bases Salts in Class 10. This test paper with questions and answers for Class 10 Science will be very useful for exams and help you to score good marks

Chapter 2 Acids Bases Salts Class 10 Science Assignment

Question. Which one of the following can be used as an acid– base indicator by a visually impaired student?
(A) Litmus
(B) Turmeric
(C) Vanilla essence
(D) Petunia leaves
Answer : C

Question. What is formed when zinc reacts with sodium hydroxide?
(a) Zinc hydroxide and sodium
(b) Sodium zincate and hydrogen gas
(c) Sodium zinc-oxide and hydrogen gas
(d) Sodium zincate and water
Answer : B

Question. Which of the following statement is correct about an aqueous solution of an acid and of a base?
(i) Higher the pH, stronger the acid
(ii) Higher the pH weaker the acid

(iii ) Lower the pH ,stronger the base
(iv) Lower the pH, weaker the base

(a) i & iii
(b) ii & iii
(c ) I & iv
(d) ii & iv
Answer : D

Question. Tooth enamel is made up of
(a) calcium phosphate
(b) calcium carbonate
(c) calcium oxide
(d) potassium sulphate
Answer : A

Question. Sodium hydroxide turns phenolphthalein solution
(a) pink
(b) yellow
(c) colourless
(d) orange
Answer : A

Question. Which one of the given is true, if a substance has a pH value of 7?
(a) The substance is a base
(b) The substance is an acid
(c) The substance is a neutral substance
(d) Either (A) or (B)
Answer : C

Question. An aqueous solution turns red litmus solution blue. Excess addition of which of the following solution would reverse the change?
(a) Baking powder
(b) Lime
(c) Ammonium hydroxide solution
(d) Hydrochloric acid
Answer : D

Question. Rain is called acid rain when its:
(a) pH falls below 7
(b) pH falls below 6
(c) pH falls below 5.6
(d) pH is above 7
Answer : C

Question. When copper oxide and dilute hydrochloric acid react, colour changes to
(a) white
(b) bluish-green
(c) blue-black
(d) black
Answer : B

Question. Generally, when certain metals react with an acid they release gas.
(a) Nitrogen
(b) Oxygen
(c) Hydrogen
d) Argon
Answer : C

Question : Name the substance which on treatment with chlorine yields bleaching powder. 
(a) CaO
(b) Ca(OH)2
(c) CuO
(d) CaCo3
Answer : B
Explanation: Bleaching powder is prepared by passing chlorine gas over dry slaked lime.
 
Question : A blue litmus paper was first dipped in dil. HCl and then in dil. NaOH solution. It was observed that the colour of the litmus paper 
(a) changed first to red and then to blue
(b) changed to red
(c) remained blue in both the solutions
(d) changed first to red and then to blue
Answer : D
Explanation: Blue paper turn in red indicate the sample is acidi(c) Blue paper that does not change color indicates the sample is a base. HCl is acidic and NaOH is base, So, dil. HCl turns blue litmus red which becomes blue again in NaOH.

 

True or False :

Question. The more alkaline a solution, the more is the pH.
Answer: True

Question. Methyl orange indicator gives red colour in acidic solution and yellow colour in basic solution.
Answer: True

Question. All the organic acids are strong acids. 
Answer: False

Question. The dilution of a concentrated acid should always be done by adding concentrated acid to water gradually with stirring.
Answer: True

Question. Glucose solution conduct electricity.
Answer: False

Question. The strength of an acid or base is measured on a scale of numbers called pH paper. 
Answer: False

 

Fill in the blanks :

Question. Potassium nitrate has pH value equal to …………. .
Answer : 7 or seven

Question. Use of mild base like …………. on the bee-stung area gives relief.
Answer : baking soda

Question. …………. is one of the raw materials for the production of baking soda.
Answer : Sodium chloride

Question. Acids turn …………. litmus solution…………. .
Answer : blue, red

Question. The presence of …………. Ca in acids is responsible for their acidic properties.
Answer : H+

Question. One of the constituents of baking powder is sodium hydrogen carbonate, the other constituent is _____________ .
Answer : tartaric acid

Question. The salts of carbonic acids are called _____________ .
Answer : carbonates

Question. Mixing an acid or base with water results in decrease in the concentration of per unit volume. This process is called
Answer : OH– ions/H3O+ ions, dilution

Question. pH of basic solution is always …………. than 7.
Answer : more/greater

Question. The three most common indicators to test for acid and bases are litmus _____________ and _____________ .
Answer : methyl orange, phenolphthalein

 

MCQ Questions for NCERT Class 10 Science Acids Bases and Salts

Very Short Question :

Question. How will you test for the gas which is liberated when hydrochloric acid reacts with an active metal? 
Answer: Bring a burning matchstick near the gas. It bums with ‘pop’ sound showing that it is hydrogen.

Question. Which gas is evolved when sodium hydroge-ncarbonate reacts with dilute hydrochloric acid?
Answer: Carbon dioxide gas is evolved.

Question. What is the colour of turmeric in soap solution?
Answer: Reddish-brown.

Question. What will happen to red litmus solution when it is added to bitter gourd extract? Is it acidic or basic?
Answer: It changes to blue. It is basic in nature.

Question. A few drops of sulphuric acid is added to water before electrolysis, why?
Answer: It makes water better conductor.

Question. What are phenolphthalein and methyl orange?
Answer: Synthetic indicators

Question. Which planet contains yellowish clouds of sulphuric acid?
Answer: Venus.

Question. What is the colour of litmus in a solution of ammonium hydroxide?
Answer: Red litmus will turn blue in ammonium hydroxide.

Question. What is litmus solution?
Answer: It is purple dye which is extracted from a plant ‘lichen’. It is used as acid-base indicator.

Question. Which gas is evolved when metal carbonates or metal hydrogen carbonate reacts with dilute acids?
Answer: CO2(g)

Question : Why does distilled water not conduct electricity, whereas rain water does?
Answer : Distilled water is a pure form of water and is devoid of any ionic species. Therefore, it does not conduct electricity. Rain water, being an impure form of water, contains many ionic species such as acids and therefore it conducts electricity.
 
Question : Why do acids not show acidic behaviour in the absence of water?
Answer : Acids do not show acidic behaviour in the absence of water, because acids dissociate into hydrogen ions only in the presence of water. It is the hydrogen ions that are responsible for the acidic behaviour.
 
Question : Five solutions A, B, C, D and E when tested with universal indicator showed pH as 4, 1, 11, 7 and 9, respectively. Which solution is
(a) neutral ?
(b) strongly alkaline?
(c) strongly acidic?
(d) weakly acidic?
(e) weakly alkaline?
Arrange the pH in increasing order of hydrogen-ion concentration.
Answer :
(a) Neutral → Solution D with pH 7
(b) Strongly alkaline → Solution C with pH 11
(c) Strongly acidic → Solution B with pH 1
(d) Weakly acidic → Solution A with pH 4
(e) Weakly alkaline → Solution E with pH 9.
The pH can be arranged in the increasing order of the concentration of hydrogen ions as: 11 < 9 < 7 < 4 < 1
 
Question :  You have two solutions. A and B, the pH of solution A is 6 and pH of solution B is 8.
Which solution has more hydrogen ion concentration? Which of this is acidic and which one is basic? 
Answer : In solution A, [H+(aq)] = 10-6 M
In solution B, [H+(aq)] = 10-8 M
The pH value of a solution varies from 0 to 14. The pH value is 0 for a very strong acid and the pH value is 14 for a very strong base. The pH value is 7 for a neutral solution.
Hence A is acidic and B is basic in nature. The concentration of hydrogen ion decreases from pH value of 0 to 14 therefore A has more hydrogen ion concentration.
 
Question : Equal lengths of magnesium ribbons are taken in test tubes A and B. Hydrochloric acid (HCl) is added to test tube A, while acetic acid (CH3COOH) is added to test tube B. In which test tube will the fizzing occur more vigorously and why?
Answer : The fizzing will occur strongly in test tube A, in which hydrochloric acid (HCl) is added. This is because HCl is a stronger acid than CH3COOH and therefore produces hydrogen gas at a faster speed due to which fizzing occurs.
 
Question : Fresh milk has a pH of 6. How do you think the pH will change as it turns into curd? Explain your answer.
Answer : The pH of milk is 6. As it changes to curd, the pH will reduce because curd is acidic in nature. The acids present in it decrease the pH.
 
Question : A milkman adds a very small amount of baking soda to fresh milk.
(a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
(b) Why does this milk take a long time to set as curd?
Answer : (a) The milkman shifts the pH of the fresh milk from 6 to slightly alkaline because in alkaline condition, milk does not set as curd easily.
(b) Since this milk is slightly basic than usual milk, acids produced to set the curd are neutralized by the base.
Therefore, it takes a longer time for the curd to set.

Question : i. A chemical compound X is used in glass and soap industry. Identify the compound and give its chemical formula.
ii. How many molecules of water of crystallisation are present in compound X?
iii. How will you prepare the above compound starting from sodium chloride? Write all relevant equations involved in the process.
Answer : i. The compound (X) is washing soda. Its chemical formula is Na2CO3 .10H2O
ii. Ten molecules of water of crystallisation are present in this compound.
iii. Ammonia and carbon dioxide gas in passed through brine (or concentrated sodium chloride solution) then a mixture of NaHCO3 and NH4Cl is formed.

a-7
 
 
Question : Plaster of Paris should be stored in a moisture-proof container. Explain why?
Answer : Plaster of Paris (POP) should be stored in a moisture-proof container because Plaster of Paris, a powdery mass, absorbs water (moisture) to form a hard solid known as gypsum.
 
Question :  Why is sodium hydrogen carbonate an essential ingredient in most antacids? 
Answer : Sodium hydrogen carbonate is slightly alkaline in nature that's why it is an essential ingredient in most antacids.
 
Question : What is a neutralization reaction? Give two examples.
Answer : When an acid mixed with a base then they react with each other to form the salt and water with the release of energy and cancel each other's effect. This process is neutralization process.
 Acid + Base → Salt + Water + Heat
Example: (1) NaOH + HCl → NaCl + H2O + Heat
(2) During indigestion (caused due to the production of excess of hydrochloric acid in the stomach),we take an antacid (generally milk of magnesia, which is basic in nature). The antacid neutralizes the excess of acids and thus gives relief from indigestion.
 
Question :  Give one example of natural indicator. 
Answer : Indicators obtained from natural sources are called natural indicators. Litmus, turmeric, red cabbage, China rose, etc. are some common natural indicators used widely to show the acidic or basic character of substances.
 
Question :  Write the formulae of the salts given below:
Potassium sulphate, sodium sulphate, calcium sulphate, magnesium sulphate, copper sulphate, sodium chloride, sodium nitrate, sodium carbonate and ammonium chloride.
Identify the acids and bases from which the above salts may be obtained. How many families can you identify among these salts? 
Answer : The following table gives the formulae of the given salts, and the acids and bases from which these salts may be obtained:
 
 a-8
 
 

Question : a) Acids are sour in taste. Is it a way to find whether a substance is an acid or a base?

b) What is other physical test?

c) Any test with solid acid?

d) Can you check the evolution of CO2 chemically?

Question : a) What are acids?

b) Can presence of H+ ion in water be estimated? How?

c) How is pH related to strength of an acid?

d) Name one strong acid and one weak acid

Question : a) What are salts?

b) How many types of salts are formed?

c) What are neutral salts?

d) What do you mean by acidic salts?

e) Define basic salts.

f) Give the corresponding acid and base from which sodium carbonate is formed

Question : a) What is common salt?

b) Why does common salt become moist in rainy season?

c) How is it used as a freezing mixture?

d) Name two important laboratory chemicals prepared from common salt on large scale.

Question : a) What is washing soda?

b) Name the process by which sodium carbonate is manufacture.

c) What are the raw materials used in the preparation of washing soda?

d) Sodium carbonate is obtained from another carbonate on heating. Name it.

Question : a) Name the substance used for bleaching cotton and wood pulp in textiles.

b) What is its chemical name?

c) How is it manufactured?

d) What is slaked lime?

e) Why does bleaching powder smell of chlorine?

 

Chapter 01 Chemical Reactions and Equations
CBSE Class 10 Science Chemical Reactions and Equations Assignment

CBSE Class 10 Science Chapter 2 Acids Bases Salts Assignment

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