CBSE Solutions for Class 10 English

જવાબ :

જવાબ : The acidic behavior from acids is because of the presence of hydrogen ions. Hydrogen ions can only be produced in the presence of water and therefore water is definitely needed if acids are to show their acidic behavior.

જવાબ : The reaction of the acid + base gives a product of salt + water, which is taken into account as neutralization .
Examples:
NaOH + HCl → NaCl + H2O
Mg(OH)2 + H2CO3 → MgCO3 + 2H2O

જવાબ : Plaster of Paris should be stored in moisture-proof container because moisture can affect plaster of Paris by slowing down the setting of the plaster due to hydration. this may turn plaster useless.

જવાબ : (a) He shifted the pH of the fresh milk from 6 to slightly alkaline to stop milk from getting sour thanks to production of carboxylic acid .
(b) This milk takes while to line into curd because the carboxylic acid produced here first neutralises the pH then the pH is reduced to show milk to curd.

જવાબ : Fresh milk is turned to curd thanks to production of carboxylic acid . carboxylic acid reduces the pH of the milk.

જવાબ : HCl may be a strong acid whereas acetic may be a weaker acid. Fizzing occurs thanks to the assembly of the hydrogen gas obtained due to reaction of the acid on the magnesium ribbon. Since HCl may be a very strong acid there's tons of liberation of hydrogen gas from tube A. therefore, more fizzing happen in tube A.

જવાબ : Indigestion is thanks to excess production of acid within the stomach. Medicines wont to treat indigestion is named as Antacid.

જવાબ : Since 10 ml of NaOH requires 8 mL of HCL, 20 ml of NaOH require 8 x 2 = 16mL of HCl Hence the solution id option d 16mL.

જવાબ : Answer is HCl.
Egg shells contains carbonate , which on reaction with HCl liberates CO2 gas which turn lime water to milky.
CaCO3 + 2HCl → CaCl2 + H2O + CO2

જવાબ : Answer is 10 because paper turns blue when reacts with basic solution (PH quite 7).

જવાબ : If the soil is acidic in nature (PH below 7) then such field should be treated with quick lime (calcium oxide) or calcium hydroxide (calcium hydroxide) or chalk (calcium carbonate).

જવાબ : Yes,Basic solutions has H+ ions, but hydroxide ions present in basic solution are more in basic solution. Hence Hydroxide ions turn solution to basic.

જવાબ : proton concentration decides the character of the answer . If proton concentration increase then solution turn acidic and similarly if proton concentration decreases then solution turn basic.

જવાબ : proton concentration decides the character of the answer . If proton concentration increase then solution turn acidic and similarly if proton concentration decreases then solution turn basic.

જવાબ : so as to seek out the proton concentration, we will use the rule that states, “The pH of any solution is inversely proportional to the proton concentration”. Therefore, it means the answer that features a lower pH number will have a better proton concentration. Hence, solution X will have a better proton concentration. additionally , solution Y are going to be basic and X are going to be acidic.

જવાબ : When base is dissolved in caustic soda solution its hydroxide ions increase but it'll reach saturation at some point. After saturation hydroxyl ion concentration isn't affected even after adding base further.

જવાબ : When acid is added to water there'll be a hard and fast amount of hydronium present within the fixed volume of solution. If we dilute the answer hydronium ion per volume of solution decrease, this in-turn decreases Hydronium concentration within the solution.

જવાબ : While diluting an acid, it's recommended that the acid should be added to water and not water to the acid because if water is added to concentrated acid, it release huge amount of warmth which can end in explosion and may cause acid burns o face, clothes and body parts. Hence it's safe to feature acid to water but not water to acid.

જવાબ : HCL doesn't give out Hydrogen ions, therefore HCL doesn't show any acidic behaviour and colour of the paper remain an equivalent on reacting with HCl gas.

જવાબ : Charged particles are liable for the conductance of electricity in an acid. These charged particles called as ions are the rationale behind conductance of electricity in acid.

જવાબ : As metal compound released is salt the gas evolved here is CO2. Hence metal X should be Calcium Carbonate. Hence the reaction between carbonate and HCl is
CaCO3 (s) + 2HCl (Aq) → CaCl2( Aq) + CO2 (g) + H2O (l)

જવાબ : When an acid reacts with any metal, salt and hydrogen gas are formed.
Metal + Acid → Salt + Hydrogen gas

જવાબ : Curd and sour food substances contain acids; these acidic substances combine with metal. This reaction turns food to poison which damage people’s health

જવાબ : The chemical equation for the reaction of Plaster of Paris and water is
CaSO4.1/2H2O + 3/2H2O → CaSO4.2H2O

જવાબ : Heating sodium hydrocarbonate yields sodium carbonate and carbon dioxide gas is liberated in the process.

જવાબ : washing soda is that the compound which is employed for softening water .

જવાબ : Calcium hydroxide.

જવાબ : bleaching powder.

જવાબ : CH3COOH

જવાબ : OH– ions/H3O+ ions, dilution

જવાબ :  H+

જવાબ : acid (HCl)

જવાબ : baking soda

જવાબ : acidic, less

જવાબ : Sodium chloride

જવાબ : Water of crystallization

જવાબ : 7

જવાબ : CaSO4, Cl2, H2O

જવાબ : greater

જવાબ : blue, red

જવાબ : neutralization

જવાબ : monobasic acid

જવાબ : yellow

જવાબ : Caustic soda

જવાબ : washing soda

જવાબ : slaked lime with chlorine

જવાબ : Mohr’s salt

જવાબ : colourless

જવાબ : gypsum

જવાબ : greater than 7

જવાબ : Strong acids are those acids which are completely ionised in aqueous solution. Weak acids are those which do not ionise completely in aqueous solution. Strong acid: HCl,  HNO₃,H₂SO₄ Weak acid: Citric acid, acetic acid, formic acid.

જવાબ : (a) Our stomach has pH equal to 2. Antacids neutralizes excess of acid in our body and gives relief from hyperacidity. Sodium hydrogencarbonate is one of such antacid.
(b) pH will decrease as it turns to curd because curd is acidic due to the presence of lactic acid.
(c) It takes longer time to set as curd as bacteria do not work well in presence of sodium hydrogencarbonate, i.e. fermentation will take place slowly.
(d) Toothpastes are basic in nature. They neutralize the acid formed in mouth which causes tooth decay.

જવાબ : (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 .

જવાબ : 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.

જવાબ : 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.

જવાબ : 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.

જવાબ : 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.

જવાબ : 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.

જવાબ :
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.

જવાબ :
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 .

જવાબ : 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.
 

જવાબ : 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.

જવાબ : 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.

જવાબ : (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.

જવાબ : (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.

જવાબ : (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.

જવાબ : (a) the answer with pH 7 is neutral. Its pH are often increased by adding alittle amount of base like caustic soda . Basic solutions have pH quite 7. Similarly, pH are often decreased by adding bit of acid like acid . Acidic solutions have pH but 7.
(b) The change in colour of litmus from red to blue indicates that the answer is of basic nature with pH quite 7.
(c) CO2 are often liberated by reacting washing soda solution with acid like dilute acid . This shows that the answer is of acidic nature with pH but 7.

જવાબ : (i) Common salt contains the impurity of magnesium chloride (MgCl2) which is of deliquescent nature. When exposed to atmosphere, it becomes moist. Therefore, common salt becomes sticky during the rainy reason.
(ii) blue copperas (CUSO4.5H2O) upon heating changes to anhydrous copper sulfate (CUSO4) which is white in colour.
(iii) Concentrated vitriol is very hygroscopic. It absorbs moisture from air and gets diluted. Since the quantity increases, the acid starts flowing out of the bottle.

જવાબ : (a) The raw materials used are : NaCl, lime stone or CaCO3 and NH3.
(b) Sodium bicarbonate (NaHCO3) is sparingly soluble or less soluble in water and gets separated as a preciptate while NH4Cl remains in solution. The precipitate is removed by filtration.
(c) Sodium bicarbonate is converted to washing soda upon heating.

જવાબ : (a)

1. Red litmus has no action on dry ammonia gas because it does not release any hydroxyl ions (OH)^–
2. When passed through water, ammonia (NH₃) is converted to ammonium hydroxide (NH₄OH). It dissociates to give hydroxyl ions (OH)^– and the solution is basic in nature. Red litmus acquires a blue colour.

1. A green precipitate of ferrous hydroxide would be formed by double displacement reaction.
   
2. A white precipitate of aluminium hydroxide will be formed by double displacement reaction.

જવાબ : (a) An aqueous solution of an acid conducts electricity because in water, an acid (e.g. HCl) dissociates to give ions. Since the current is carried by the movement of ions, an aqueous solution of acid conducts electricity.
(b) Upon dilution, more of acid dissociates into ions. Therefore, concentration of [H₃O]⁺ ions increases upon dilution.
(c) Although more [H₃O]⁺ ions are formed upon dilution, but the number of ions per unit volume decrease. Therefore, pH will increase upon dilution.
(d)

1. Carbon dioxide gas would evolve accompanied by brisk effervescene.
   NaHCO₃ (s) + HCl (aq) ———–> NaCl(aq) + CO₂(g) + H₂O(aq)
2. Hydrogen gas would evolve accompanied by brisk effervescene.
   Zn(s) + 2HCl (aq) ———–> ZnCl₂(ag) + H₂(g)

જવાબ : (a) Upon heating sodium chloride with cone. H₂SO₄, hydrogen chloride gas evolves.
NaCl(s) + H₂SO₄(aq) ———> NaHSO₄ (aq) + HCl (g)
In the gaseous state, the acidic character is not shown because HCl does not release any H⁺ ions. In the presence of moisture (moist litmus paper), the gas changes to hydrochloric acid i.e., HCl(aq). The acid releases H⁺ ions and thus, shows acidic character. Therefore, moist blue litmus paper becomes red.
(b) When fresh milk changes to curd, the pH of the solution is likely to decrease. Actually, lactose present in milk gets converted to lactic acid when curd or yogurt is formed from milk. Therefore, the medium becomes more acidic and its pH decreases.
(c) The solution of sodium carbonate (Na₂CO₃) is of basic nature. Actually, the salt dissolves in water to produce NaOH (strong base) and H₂CO₃(weak acid). The blue litmus will not undergo any change in the basic medium. It will remain blue.

જવાબ : (i) The gas ‘X’ is H₂ and gas ‘Y’ is Cl₂
(ii) The chemical equation for the reaction is :

(iii) Cl₂ reacts with slaked lime to form bleaching powder.
Ca(OH)₂ + Cl₂ ———–> CaOCl₂ + H₂O.

જવાબ : (i) The strength of an acid is expressed in terms of its H⁺ ions releasing tendency in aqueous solution or in terms of its degree of dissociation
(α). Strong acids have large value of α (close to one) while weak acids have comparatively less value. For example, hydrochloric acid (HCl) is a strong acid while acetic acid (CH₃COOH) is a weak acid.
(ii) The available information suggests that the base ‘B’ present in the pellet is sodium hydroxide (NaOH). It is of deliquescent nature. It absorbs moisture from atmosphere and becomes sticky. The base reacts with dilute hydrochloric acid to form salt and water. This reaction is known as neutralisation reaction.
NaOH (aq) + HCl(aq) ———–> NaCl (aq) + H₂O(l)

જવાબ : Sodium chloride (NaCl) also called common salt or table salt is the most essential part of our diet. Chemically it is formed by the reaction between solutions of sodium hydroxide and hydrochloric acid. Sea water is the major source of sodium chloride where it is present in the dissolved form alongwith other soluble salts such as chlorides and sulphates of calcium and magnesium. It is separated by some suitable method. Deposits of the salt are found in different parts of the world and is known as rock salt. The formation of rock salt is due to the slow evaporation of sea water which takes ages. When pure, it is a white crystalline solid. However, it is often brown due to the presence of impurities.
• Sodium Chloride — Essential for Life
Sodium chloride is quite essential for life. Biologically, it has a number of functions to perform such as in muscle contraction, in conduction of nerve impulses in the nervous system and is also converted into hydrochloric acid in the stomach which helps in the digestion of food. When we sweat, there is loss of sodium chloride and some. Other salts alongwith water. This leads to muscle cramps. The loss has to be compensated suitably by giving certain salt preparations to the patients. These are called electrolytes Electral powder is a very popular electrolyte.
• Chemicals from Common Salt
Sodium chloride is also a very useful raw material for different chemicals. A few out of these are : hydrochloric acid (HCl), washing soda (Na₂CO₃-10H₂O), baking soda (NaHCO₃) etc. Upon electrolysis, a strong solution of the salt (brine), sodium hydroxide, chlorine and hydrogen are obtained.
Apart from these, it is used in leather industry for the leather tanning. In severe cold, rock salt is spread on icy roads to melt ice. It is also, a fertilizer for sugar beet.

જવાબ : Sodium chloride (NaCl) also called common salt or table salt is the most essential part of our diet. Chemically it is formed by the reaction between solutions of sodium hydroxide and hydrochloric acid. Sea water is the major source of sodium chloride where it is present in the dissolved form alongwith other soluble salts such as chlorides and sulphates of calcium and magnesium. It is separated by some suitable method. Deposits of the salt are found in different parts of the world and is known as rock salt. The formation of rock salt is due to the slow evaporation of sea water which takes ages. When pure, it is a white crystalline solid. However, it is often brown due to the presence of impurities.
• Sodium Chloride — Essential for Life
Sodium chloride is quite essential for life. Biologically, it has a number of functions to perform such as in muscle contraction, in conduction of nerve impulses in the nervous system and is also converted into hydrochloric acid in the stomach which helps in the digestion of food. When we sweat, there is loss of sodium chloride and some. Other salts alongwith water. This leads to muscle cramps. The loss has to be compensated suitably by giving certain salt preparations to the patients. These are called electrolytes Electral powder is a very popular electrolyte.
• Chemicals from Common Salt
Sodium chloride is also a very useful raw material for different chemicals. A few out of these are : hydrochloric acid (HCl), washing soda (Na₂CO₃-10H₂O), baking soda (NaHCO₃) etc. Upon electrolysis, a strong solution of the salt (brine), sodium hydroxide, chlorine and hydrogen are obtained.
Apart from these, it is used in leather industry for the leather tanning. In severe cold, rock salt is spread on icy roads to melt ice. It is also, a fertilizer for sugar beet.

જવાબ : (a)CuSO₄.5H₂O is hydrated copper sulphate. CuSO₄ is anhydrous copper sulphate.
Aim: To show crystalline salts contain water of crystallization.
Material Required: CuSO₄.5H₂O (Blue vitriol), boiling tube, burner, cork,
delivery tube, test tube, clamp stand.
Procedure: 1.Take 2g of CuSO₄.5H₂O in a boiling tube fitted in a clamp stand.
2.Observe its colour. Fit it with cork and delivery tube bent at two right angles which dips into a test tube.
3.Heat crystals in boiling tube.
4.Observe vapours being condensed in test tube.
5.Cool the crystals and add few drops of water into it.
Observation:Water vapours get condensed in a test tube and colour
of blue crystals changes into white. On adding water to anhydrous copper sulphate it changes into blue again.
Chemical Reaction :

Conclusion : Crystalline substances have water of crystallization which are lost on heating. When we add water inCuSO₄till a saturated solution is formed. On cooling, it gets converted into CuSO₄.5H₂Ocrystals and it shows that both are inter convertible.

જવાબ : Baking powder.
It consist of sodium hyrogencarbonate and tartaric acid.
Sodium hydrogencarbonate gives CO₂ which makes cake soft and fluffy. Tartaric acid neutralizes the bitterness due to sodium carbonate produced.

જવાબ : (i) X is sodium hydroxide, NaOH.
When sodium chloride solution (brine solution) is electrolysed, sodium hydroxide solution is formed. H2 and Cl2 gases are liberated. This is chlor-alkali process.

The above reaction is neutralization reaction.
(ii)It is because process is highly exothermic. If water is added to acid, bottle of acid will break.

જવાબ : (a) HCl is acid and NaOH is base whose combination forms the common salt. Its formula is NaCl (Sodium chloride). It is obtained from sea water.
(b) Rock salt is the common name for the mineral “halite”. Its chemical formula is NaCl.
It may be white or light blue or yellow depending upon impurities present in it.

જવાબ :

જવાબ :

Column (A) Column (B)

(a) Lactic acid (iv) Curd

(b) Acetic acid (iii) Vinegar

(c) Citric acid (ii) Lemon

(d) Oxalic acid (i) Tomato

જવાબ :

a. Hydrogen

b. Neutralisation

c. Base
d. Antacid

જવાબ :

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

જવાબ :

જવાબ :

જવાબ :

જવાબ :

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