10th Science - Book Back Answers - Chemistry Unit 9 - English Medium Guides

 

1. I. Choose the correct Answer
2. II. Fill in the blanks
3. III.Match the Following
4. IV.  True or False
5. V.  Short answer
6. VI. Long answer
7. VII. HOTS

SSLC / 10th - Science - Book Back Answers - Chemistry Unit 9 - English Medium

Tamil Nadu Board 10th Standard  Science - Chemistry Unit 9: Book Back Answers and Solutions

    This post covers the book back answers and solutions for Unit 9 – Physics from the Tamil Nadu State Board 10th Standard  Science textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.

    We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.

    By going through this material, you’ll gain a strong understanding of Chemistry unit 9 along with the corresponding book back questions and answers (PDF format).

Question Types Covered:

• 1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following 
• 2 Mark Questions: Answer briefly 
• 3, 4, and 5 Mark Questions: Answer in detail

All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.

All the best, Class 10 students! Prepare well and aim for top scores. Thank you!

Topic: Solutions

I. Choose the correct Answer

I. Choose the best Answer Key:
 1. A solution is a mixture.
(a) homogeneous
(b) heterogeneous
(c) homogeneous and heterogeneous
(d) non-homogeneous
Answer Key:
(a) homogeneous
 
2. The number of components in a binary solution is ______.
(a) 2
(b) 3
(c) 4
(d) 5.
Answer Key:
(a) 2
 
3. Which of the following is the universal solvent?
(a) Acetone
(b) Benzene
(c) Water
(d) Alcohol
Answer Key:
(c) Water
 
4. A solution in which no more solute can be dissolved in a definite amount of solvent at a given temperature is called ______.
(a) Saturated solution
(b) Un saturated solution
(c) Supersaturated solution
(d) Dilute solution.
Answer Key:
(a) Saturated solution
 
5. Identify the non-aqueous solution.
(a) sodium chloride in water
(b) glucose in water
(c) copper sulphate in water
(d) sulphur in carbon-di-sulphide
Answer Key:
(d) sulphur in carbon-di-sulphide
 
6. When pressure is increased at a constant temperature the solubility of gases in liquid ______.
(a) No change
(b) increases
(c) decreases
(d) no reaction.
Answer Key:
(b) increases
 
7. Solubility of NaCl in 100 ml water is 36 g. If 25 g of salt is dissolved in 100 ml of water how much more salt is required for saturation:
(a) 12 g
(b) 11 g
(c) 16 g
(d) 20 g
Answer Key:
(b) 11 g
 
8. A 25% alcohol solution means ______.
(a) 25 ml of alcohol in. 100 ml of water
(b) 25 ml of alcohol in 25 ml of water
(c) 25 ml of alcohol in 75 ml of water
(d) 75 ml of alcohol in 25 ml of water.
Answer Key:
(c) 25 ml of alcohol in 75 ml of water
 
9. Deliquescence is due to:
(a) Strong affinity to water
(b) Less affinity to water
(c) Strong hatred to water
(d) Inertness to water
Answer Key:
(a) Strong affinity to water
 
10. Which of the following is hygroscopic in nature?
(a) ferric chloride
(b) copper sulphate pentahydrate
(c) silica gel
(d) none of the above.
Answer Key:
(c) silica gel

II. Fill in the blanks

1. The component present in lesser amount, in a solution is called ……..
2. Example for liquid in solid type solution is ……….
3. Solubility is the amount of solute dissolved in ……… g of solvent.
4. Polar compounds are soluble in ……… solvents.
5. Volume percentage decreases with increases in temperature because ………
Answer Key:
1. solute
2. amalgam
3. 100
4.Polar
5.of expansion of liquid

III.Match the Following

Column I		Column II
1	Blue vitriol	i	CaSO4 .2H2O
2	Gypsum	ii	CaO
3	Deliquescence	iii	CuSO4 .5H2O
4	Hygroscopic	iv	NaOH

Answer Key:

Column I		Column II
1	Blue vitriol	iii	CuSO4 .5H2O
2	Gypsum	i	CaSO4 .2H2O
3	Deliquescence	iv	NaOH
4	Hygroscopic	ii	CaO

IV.  True or False

1. Solutions which contain three components are called binary solution.
2. In a solution the component which is present in lesser amount is called solvent.
3. Sodium chloride dissolved in water forms a non-aqueous solution.
4. The molecular formula of green vitriol is MgSO4. 7H2O
5. When Silica gel is kept open, it absorbs moisture from the air, because it is hygroscopic in nature.
Answer Key:
1. False – Solutions which contain two components are called binary solution.
2. False – In a solution the component which is present in lesser amount is called solute.
3. False – Sodium chloride dissolved in water forms an aqueous solution.
4. False – The molecular formula of green vitriol is FeSO4. 7H2O
5. True

V.  Short answer

1. Define the term: Solution
Answer Key:
A solution is a homogeneous mixture of two or more substances.

2. What is mean by the binary solution?
Answer Key:
A solution must at least be consisting of two components. Such solutions which are made of one solute and one solvent are called binary solutions.
E.g., On adding CuSO₄ crystals to water.

3. Give an example each
1.gas in liquid;
2.solid in liquid;
3.solid in solid;
4.gas in gas.
Answer Key:
1.Gas in liquid – CO₂ in water
2.Solid in liquid – NaCl in water
3.Solid in solid – Alloys
4.Gas in gas – He – O₂ gas

4. What is the aqueous and non-aqueous solution? Give an example.
Answer Key:
Aqueous solution: The solution in which water act as a solvent is called aqueous solution. In general, ionic compounds are soluble in water and form aqueous solutions more readily than covalent compounds. E.g. Common salt in water.
Non – Aqueous solution: The solution in which any liquid, other than water act as a solvent is called non-aqueous solution. Alcohols, benzene, ethers, etc., are used as non – aqueous solvents. E.g. Sulphur dissolved in carbon disulphide.

5. Define Volume percentage.
Answer Key:
Volume percentage is defined as the percentage by volume of solute (in ml) present in the given volume of solution.
$\mathbf{V}\mathbf{o}\mathbf{l}\mathbf{u}\mathbf{m}\mathbf{e}\mathbf{ }\mathbf{P}\mathbf{e}\mathbf{r}\mathbf{c}\mathbf{e}\mathbf{n}\mathbf{t}\mathbf{a}\mathbf{g}\mathbf{e}\mathbf{=}\frac{\mathbf{V}\mathbf{o}\mathbf{l}\mathbf{u}\mathbf{m}\mathbf{e}\mathbf{ }\mathbf{o}\mathbf{f}\mathbf{ }\mathbf{t}\mathbf{h}\mathbf{e}\mathbf{ }\mathbf{s}\mathbf{o}\mathbf{l}\mathbf{u}\mathbf{t}\mathbf{e}}{\mathbf{V}\mathbf{o}\mathbf{l}\mathbf{u}\mathbf{m}\mathbf{e}\mathbf{ }\mathbf{o}\mathbf{f}\mathbf{ }\mathbf{s}\mathbf{o}\mathbf{l}\mathbf{u}\mathbf{t}\mathbf{e}}\mathbf{\times }\mathbf{100}$

                                   

6. The aquatic animals live more in a cold region. Why?
Answer Key:
Aquatic animals live more in cold regions because the solubility of oxygen is more in cold water (at low temperature). Therefore, aquatic animals are more comfortable in cold water.

7. Define Hydrated salt.
Answer Key:
Ionic substances which crystallise out from their saturated aqueous solution with a definite number of molecules of water are called hydrated salts.

8. A hot saturated solution of copper sulphate forms crystals as it cools. Why?
Answer Key:
The capability of a solution to maintain a certain concentration of solute is temperature-dependent. When a saturated solution of copper sulphate at above room temperature is allowed to cool, the solution becomes supersaturated and in the absence of stirring or the return of the previous solution temperature, the solute starts to precipitate out. i.e., crystal formation occurs.
 
9. Classify the following substances into deliquescent, hygroscopic. Cone. Sulphuric acid, Copper sulphate penta hydrate, Silica gel, Calcium chloride and Gypsum salt.
Answer Key:

Deliquescent	Hygroscopic
Calcium chloride	conc.${\mathbf{H}}_{\mathbf{2}}\mathbf{S}{\mathbf{O}}_{\mathbf{4}}$
	$\mathbf{C}\mathbf{u}\mathbf{S}{\mathbf{O}}_{\mathbf{4}}\mathbf{.}\mathbf{5}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}$
	Silica gel
	$\mathbf{C}\mathbf{a}\mathbf{S}{\mathbf{O}}_{\mathbf{4}}\mathbf{.}\mathbf{2}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{\left(}\mathbf{G}\mathbf{y}\mathbf{p}\mathbf{s}\mathbf{u}\mathbf{m}\mathbf{\right)}$

 

VI. Long answer

1. Write notes on?
(i)saturated solution
(ii)unsaturated solution
Answer Key:

1. Saturated solution: A solution in which no more solute can be dissolved in a definite amount of the solvent at a given temperature is called saturated solution, e.g. 36 g of sodium chloride in 100 g of water at 25°C forms a saturated solution.
2.Unsaturated solution: Unsaturated solution is one that contains less solute than that of the saturated solution at a given temperature, e.g. 10 g or 20 g or 30 g of Sodium chloride in 100 g of water at 25°C forms an unsaturated solution.
 
2. Write notes on various factors affecting solubility.
Answer Key:
There are three main factors which affects the solubility of a solute. They are
1. Nature of the solute and solvent
2. Temperature
3. Pressure
1. Nature of the solute and solvent : The nature of the solute and solvent plays an important role in solubility. Even though water is Universal solvent, all substances do not dissolve in water. Dissolution occurs when similarities exist between the solvent and the solute.
Ionic compounds are soluble in polar solvent like water and covalent compounds are soluble in non-polar solvents like ether, benzene, alcohol etc.

2. Effect of Temperature :
Solubility of solid in liquid : Generally solubility of a solid solute in a liquid increases with increase in temperature.
In Endothermic process : Solubility increases with increase in temperature.
In Exothermic process : Solubility decreases with increase in temperature.
Solubility of Gases in liquid : Solubility of gases in liquid decreases with increase in temperature.

3. Effect of Pressure : Effect of pressure is observed only in the case of solubility of a gas in a liquid. When the pressure is increased, the solubility of a gas in liquid increases.
 
3. (a) What happens when MgSO₄.7H₂O is heated? Write the appropriate equation
(b) Define solubility.
Answer Key:
(a) When Epsom salt MgSO₄.7H₂O crystals are gently heated, it loses seven water molecules and becomes anhydrous MgSO₄.
 
(b) Solubility is defined as the amount of solute in grams that can be dissolved in 100 g of the solvent to form its saturated solution at a given temperature and pressure.

$\mathrm{Solubility}=\frac{\mathrm{Mass} \mathrm{of} \mathrm{the} \mathrm{solute}}{ \mathrm{Mass} \mathrm{of} \mathrm{the} \mathrm{solvent}}\times 100$
 
4. In what way hygroscopic substances differ from deliquescent substances.
Answer Key:

Hygroscopic substances	Deliquescence substances
When exposed to the atmosphere at ordinary temperature, they absorb moisture and do not dissolve.	When exposed to the atmospheric air at ordinary temperature, they absorb moisture and dissolve.
Hygroscopic substances do not change its physical state on exposure to air.	Deliquescent substances change its physical state on exposure to air.
Hygroscopic substances may be amorphous solids or liquids.	Deliquescent substances are crystalline solids.

5. A solution is prepared by dissolving 45 g of sugar in 180 g of water. Calculate the mass percentage of solute.
Answer Key:
Mass of the solute (sugar) = 45 g
Mass of the solvent (Water) = 180 g
Formula:
Mass percentage of solute (sugar)
$=\frac{\mathrm{Mass} \mathrm{of} \mathrm{the} \mathrm{solute}}{\mathrm{Mass} \mathrm{of} \mathrm{the} \mathrm{solute} + \mathrm{Mass} \mathrm{of} \mathrm{the} \mathrm{solvent}}\times 100$

$=\frac{45}{45+180}\times 100$

$=\frac{45}{225}\times 100=20\%$
The mass percentage of solute = 20%
 
6. 3.5 litres of ethanol is present in 15 litres of aqueous solution of ethanol. Calculate volume percent of ethanol solution.
Answer Key:
Volume of ethanol = 3.5 lit = 3500 ml
Volume of water = 15 lit = 15000 ml
Formula:

Volume percentage

$\mathrm{}$

$=\frac{3500}{3500+15000}\times 100=18.92\%$
The volume percentage of ethanol solution = 18.92

VII. HOTS

1. Vinu dissolves 50 g of sugar in 250 ml of hot water, Sarath dissolves 50 g of same sugar in 250 ml of cold water. Who will get a faster dissolution of sugar? and Why?
Answer Key:
Vinu will get a faster dissolution of sugar. Because generally solubility of a solid solute in a liquid solvent increases with increase in temperature. Therefore Vinu dissolves 50 g of sugar in 250 ml of hot water than Sarath dissolves 50 g of sugar in 250 ml of cold water.
 
2. ‘A’ is a blue coloured crystalline salt. On heating it loses blue colour and to give ‘B’ When water is added, ‘B’ gives back to ‘A’. Identify A and B, write the equation.
Answer Key:
Since ‘A’ is a blue coloured crystalline salt, it is CuSO₄. 5H₂O (Blue vitriol). On heating it loses all five water molecules and becomes colourless anhydrous CuSO₄.
asas
When water is added ‘B’ gives back A.

3. Will the cool drinks give more fizz at top of the hills or at the foot? Explain.
Answer Key:
At hilltops, the temperature will become less and pressure also decreases. Because temperature and pressure are directly proportional to each other. At low-pressure carbonate, cool drinks will give less fizz and give more fizz at the foot.