CBSE Solutions for Class 10 Maths

Select CBSE Solutions for class 10 Subject & Chapters Wise :

Fill in the blanks :-  …………. is the fixed number of water molecules chemically attached to every formula unit of a salt in its crystalline form.

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Answer :

Water of crystallization

Fill in the blanks :-  saltpeter has pH value adequate to …………. .

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Answer :

7

Fill in the blanks :-  …………. are obtained when bleaching powder reacts with dilute sulphuric acid.

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Answer :

CaSO4, Cl2, H2O

Fill in the blanks :-  The pH of basic solution is always …………. than 7.

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greater

Fill in the blanks :-  Acids turn …………. litmus solution into …………. .

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blue, red

Fill in the blanks :- The process of formation of salt and water when an acid reacts with a base is called ……………. Process.

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neutralization

Fill in the blanks :- Boric acid is a …………….

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monobasic acid

Fill in the blanks :- The color of methyl orange in basic medium is …………….

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yellow

Fill in the blanks :- ……………. Soda is a deliquescent solid.

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Caustic soda

Fill in the blanks :- Hardness of water can be removed by …………….

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washing soda

Fill in the blanks :- Bleaching powder can be made by reacting …………….

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slaked lime with chlorine

Fill in the blanks :- An example of double salt is …………….

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Mohr’s salt

Fill in the blanks :- Phenolphthalein is ……………. in a acidic solution.

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colourless

Fill in the blanks :- Plaster of Paris is obtained from …………….

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gypsum

Fill in the blanks :- When a solution turns red litmus blue, its pH is likely to be …………….

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Answer :

greater than 7

You have been given three test tubes. one among them contains water and therefore the other two contain an acidic solution and a basic solution, respectively. If you're given only red paper , how will you identify the contents of every tube ?

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Answer :

(i) Put the red paper altogether the test tubes, turn by turn. the answer which turns red litmus to blue are going to be a basic solution. The blue paper formed here can now be wont to test the acidic solution.
(ii) Put the blue paper obtained above within the remaining two test-tubes, turn-by-turn. the answer which turns the blue paper to red are going to be the acidic solution.
(iii) the answer which has no effect on any paper are going to be neutral and hence it'll be water .

An alkali is a crucial base used for the laboratory work. Name the bottom and state how it are often prepared from common salt? what's this process called?

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Answer :

An important alkali commonly needed for laboratory work is caustic soda . It are often prepared from common salt by the method of electrolysis. this is often called chlor-alkali process.
Electrolysis of solution of common salt : When electricity is skilled an solution of sodium chloride commonly called brine, it decomposes into chloride and sodium. Sodium is collected at the cathode where it reacts with water to make caustic soda . Chlorine is made at the anode and is collected as a gas.

electrolysis of NaCl

Cathode:

sodium hydroxide

At Anode:

Chlorine

The overall reaction is

chlor-alkali process

What are acids? Name a number of their properties.

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Answer :

Acids are those chemical which produce hydrogen ions in its solution for example: acid , vitriol , acid etc.
Properties of Acids are
(i) it's sour in taste.
(ii) It turns blue litmus into red.
(iii) It turns azo dye colour into red.
(iv) Acids has corrosive in nature.

what's meant by bases? Write their properties.

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Answer :

Bases are those chemical which produce hydroxide ions (OH-) in its solution for example: caustic soda , lime , milk of magnesia etc.
Properties of Bases are
(i) Base has bitter in taste.
(ii) Base convert red litmus into blue.
(iii) Base convert azo dye colour into yellow.
(iv) Base convert the color of Phenolphthalein into pink.
(v) Base doesn't react with metal.
(vi) Base doesn't react with metal carbonate and metal hydroxide carbonate thanks to its basic nature.
(vii) Only alkali bases are good conductor of electricity.

Describe the preparation of litmus solution.

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Answer :

Litmus solution may be a purple dye which is extracted from a plant lichen. This dye is employed an indicator to tests for acids and bases. When litmus solution is neither acidic nor basic, its colour is purple. Acids change the color of blue litmus to red. Bases changes the red colour to blue.

Describe the method of dissolving acids or bases in water.

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Answer :

When we dilute an acid with water then addition of acid in water may be a correct way of dilution because when water is added into acid then chemical reaction happen and much of warmth begin from the tube . thanks to which it can harm us while acid is added to water then endo thermic reaction happen thanks to assumption of warmth in water.

What does one understand by the term, “Ph scale”? what's the important use of this in our daily lives?

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Answer :


pH scale may be a scale for measuring hydrogen ions concentration. pH range between 0 to 14 thus, pH may be a number which indicate the acidic or basic nature of an answer . The neutral value of pH is 7. a worth but 7 represent an acidic solution, while a worth of quite 7 represent the essential nature of the answer .
Importance of pH in our daily life:
(i) pH of soil within the backyard: Every plant requires a selected pH for healthy growth. The optimum pH required for growth of a plant are often known by finding the pH of the place where such plant grow.
(ii) pH of our digestive system: Our stomach produce HCL which helps within the digestion of food. When the stomach has produce an excessive amount of acid we feel pain and irrigation which are the indication of indigestion. To face this problem we take antacid which neutralize excess acid and convey relief.
(iii) pH changes as explanation for tooth decay: enamel is phosphate and is that the hardest substance within the body. It doesn't dissolve with water buts gets corrode at pH below 5.5. Bacteria present within the mouth produce acid by dehydration of food particle left within the mouth after eating and thus spoil the teeth.
(iv) Plants and animal are pH sensitive: Living organism can survive within the narrow range (7.0 to 7.8) of pH. When acid precipitation flows into the river its lower the pH value and make survival of aquatic life difficult.

Discuss about Baking soda

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Answer :


i)Chemical Name: Sodium: Bi carbonate
(ii) Chemical Formula: NaHCO3
(iii) Formation: NaCl + CO2 + H2O → NH4Cl + NaHCO3
(iv) Colour and state: it's a white crystalline solid.
(v) Action of air: it's stable in air.
(vi) Solubility in water: it's soluble in water the answer are going to be alkali.
NOTE: We use bicarbonate of soda in bakery or in kitchen because once we add bicarbonate of soda in any substance it makes the food fluffy. Their CO2 is liable for the fluffiness of food like in cake. In bakery leaven is employed rather than bicarbonate of soda because leaven contain mild acid like hydroxy acid .
(vii) Uses of Baking soda: it's utilized in kitchen.
It is also utilized in medicine as antacid.
It is utilized in soda acid extinguisher .

What sort of precautions are used while handling acids within the laboratory?

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Answer :

All living things are very sensitive to acids and an excessive amount of acid can kill cells or stop proper working of cells. Concentrated acid are very dangerous and will never be handled without protection.
The following projection must be observed while handling acids.
(i) Never attempt to touch or taste acid which are utilized in the laboratory.
(ii) Never add water into concentrated acid otherwise bottle will break. Always add conc. Acid to water very slowly with continuous cooling under running water.
 

An oldster complained about acute pain within the stomach. Doctor gave him alittle antacid tablet and he got immediate relief. Explain what actually happened ?

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Answer :

The oldster was affected by acute acidity. Antacid tablet contains sodium bicarbonate (NaHCO3). It reacts with the acid (HCl) formed due to acidity and neutralizes its effect. that's how the oldster got relief.

A doctor applied surgical bandages on the fractured bones. What changes are likely to occur ?

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Answer :

Surgical bandages are made up of Plaster of Paris. When applied on the fractured bones after making them wet, it changes into a tough mass called Gypsum.

Previous Year Question Papers for CBSE Class 10 Science Chapter 2 Acids, Bases and Salts 9

The hard mass keeps the bones in proper position and therefore the gap is slowly filled due to calcification that's happening on the broken parts. This helps in uniting broken bones and that they change to one piece again.

Explain with reasons :
(i) hydroxy acid may be a component of leaven utilized in making cakes.
(ii) Gypsum, CaSO4.2H2O is employed within the manufacture of cement.

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Answer :

(i) Role of hydroxy acid in leaven (mixture of hydroxy acid and sodium bicarbonate ) is to neutralise washing soda formed upon heating sodium hydrogen carbonate.

In case it's not done, cake are going to be bitter and washing soda also will have injurious side effects.
(ii) The role of gypsum (CaSO4.2H2O) within the manufacture of cement is to hamper the method of setting of cement.

State the property in each case :
(i) as an antacid.
(ii) as a constituent of leaven .

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Answer :

(i) it's weakly alkaline in nature and neutralizes acid (HCl) formed within the stomach.
NaHCO3 + HCl ———-> NaCl + H2O + CO2
(ii) It evolves CO2 within the sort of bubbles when cake is formed by baking. As a result, the cake becomes porous also as fluffy.

Some Crystals of copper sulfate are heated during a tube for a few time.
(a) what's the color of copper sulfate crystals (i) before heating (ii) after heating ?
(b) what's the source of liquid droplets seen on the inner top of the tube during the heating process ?

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Answer :

(a) Colour of crystals before heating : blue.
Colour of crystals after heating : white.
(b) The liquid droplets formed within the inner top of the tube during the heating process are of water. it's released from the crystals of copper sulfate during heating.

Match the following

A synthetic indicator

Nettle

 Substance formed by hydration of plaster of Paris
 

Acid

A herbaceous plant with stinging hairs
 

Phenolphthalein

. Solution with pH less than 7
 

Gypsum

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Answer :

  1. Phenolphthalein
  2. Gypsum
  3. Nettle
  4. Acid

Column I

Column II

(a) Mixed salts

(p) CaCO3 MgCO3

(b) Double salts

(q) NaKCO3

(c) Basic salts

(r) NaHSO4

(d) Acidic salts

(s) CH3COONa

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Answer :

Column I

Column II

(a) Mixed salts

(q) NaKCO3

(b) Double salts

(p) CaCO3 MgCO3

(c) Basic salts

(s) CH3COONa

(d) Acidic salts

(r) NaHSO4

Column I

Column II

(a) Baking soda

(p) NaCl

(b) Plaster of Paris

(q) NaHCO3

(c) Washing soda

(r) CaSO. 1/2 H2O.

(d) Common salt

(s) Na2CO3

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Answer :

Column I

Column II

(a) Baking soda

(q) NaHCO3

(b) Plaster of Paris

(r) CaSO. 1/2 H2O.

(c) Washing soda

(s) Na2CO3

(d) Common salt

(p) NaCl

Column I

Column II

(a) Sodium carbonate

(P) Fire-proofing material

(b) Plaster of Paris

(q) Use for faster cooking

(c) Bleaching powder

(r) Softening hard water

(d) Baking soda

(s) Textile industry

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Answer :

Column I

Column II

(a) Sodium carbonate

(r) Softening hard water

(b) Plaster of Paris

(P) Fire-proofing material

(c) Bleaching powder

(s) Textile industry

(d) Baking soda

(q) Use for faster cooking

Match the chemical substances given in Column (A) with their appropriate application given in Column (B).

Column I

Column II

(A) Bleaching powder

(i) Preparation of glass

(B) Baking soda

(ii) Production of H2 and Cl2

(C)Washing soda

(iii) Decolourisation

(D) Sodium chloride

(iv) Antacid

(a) A-(ii), B-(i), C-(iv), D-(iii)
(b) A-(iii), B-(ii), C-(iv), D-(i)
(c) A-(iii), B-(iv), C-(i), D-(ii)
(d) A-(ii), B-(iv), C-(i), D-(iii)

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Answer :

(c) A-(iii), B-(iv), C-(i), D-(ii)

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