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According to ideal gas equation, 

PV = nRT

n = \(\frac{PV}{RT}\)

Now, for a known mass ‘m’ of gas having molar mass ‘M’, number of moles ‘n’ is given as:

n = \(\frac{m}{M}\)

Therefore, \(\frac{m}{M}\) = \(\frac{PV}{RT}\)

On rearranging the equation, we get

M = \(\frac{mRT}{PV}\)

A straight line parallels to pressure axis.

The correct answer is (i) Shimla

Applications of surface tension:

• Cleaning action of soap and detergent is due to the lowering of interfacial tension between water and oily substances. Due to lower surface tension, the soap solution penetrates into the fibre, surrounds the oily substance and washes it away.
• Efficacy of toothpastes, mouthwashes and nasal drops is partly due to presence of substances having lower surface tension. This increases the efficiency of their penetrating action.

Surface tension is a temperature dependent property. When attractive forces are large, surface tension is large. Surface tension decreases as the temperature increases. With increase in temperature, kinetic energy of molecules increases. So, intermolecular forces of attraction decrease, and thereby surface tension decreases.

(i) The force acting parallel to the surface and perpendicular to a line of unit length anywhere in the surface is called surface tension. Its unit is Nm^-1.

(ii) The force of friction which one part of the liquid offers to another part of the liquid is called viscosity. Its unit is poise.

(i) Liquid tends to have a minimum surface area due to surface tension. For a given volume of a liquid, sphere has the minimum surface area. So, the small drops of liquid are spherical in nature.

(ii) Surface tension decreases with increase in temperature because force acting per unit length decreases due to increase in kinetic energy of molecules.

(i) Surface Energy: The energy required to increase the surface area of the liquid by one unit is called surface energy. 

(ii) The temperature at which the density of water is maximum, is 4°C. 

(iii) Moist soil grains are pulled together due to strong forces existing between soil grains i.e. coherent forces

The correct answer is (ii) Nsm^–2

(i) S.I. unit of surface tension = Nm^-1

(ii) S.I. unit of coefficient of viscosity = Nm^-2 s or Kg ms^-1 s^-1

(i) Coefficient of Viscosity: It is defined as the force when velocity gradient \(\frac{du}{dz}\)and area of contact (A) both are unity.

F = \(\eta\)A\(\frac{du}{d\mathrm{x}}\)

F = \(\eta\) x 1 x 1 = \(\eta\)

Where F = Force

\(\eta\) = Coefficient of viscosity

In cgs system, the unit of coefficient of viscosity is poise or g cm^-1s^-1.

(ii) Difference between boiling and evaporation:

Viscosity of a liquid is a measure of resistance to flow which arises due to the internal friction between the layers of fluid as they slip one another while liquid flows. SI unit of coefficient of viscosity is Nsm^-2 or kg m^-1 s^-1 

The units of coefficient of viscosity is Poise.

In physical change, only the physical state of the substance changes but its chemical composition remains same. However, in chemical change substance with different chemical properties and composition is formed.

The slow process of decay or oxidation of metals due to various components of atmosphere is known as corrosion.

Iron rusts and a reddish coloured layer is collected on it. This is corrosion of iron.

1. (i) Increases

2. (ii) Calcium oxide

3. (iv) Combination reaction

4. (i) CaO(s) + H₂O(l) → Ca(OH)₂(aq)

5. (i) TRUE

For Sulphur:

Molar mass of S = 32g/mol

Sulphur is made up of 8 Sulphur atoms.

Hence, molar mass of Sulphur (S8) is:

8 × 32mol/g = 256mol/g

For phosphorus:

Molar mass of P = 31g/mol

Phosphorus molecule is made up of 4 phosphorus atoms.

Hence, molar mass of Sulphur (P4) is:

4 × 31mol/g = 124 mol/g

Balanced equation: 2Al + 3CuCl₂→ 2AlCl₃ + 3Cu

Step 1: Write the unbalanced equation 

Al + CuCl₂→ AlCl₃ + Cu

Step 2: Compare the number of atoms of reactants with the number of atoms of products.

Step 3: Now, first we consider the element having unequal no. of atoms on both sides. Thus, first let us consider the chlorine atom. If we multiply 3 in the reactant (in CuCl₂) and 2 in the product (AlCl₃), we will get the equal number of atoms in both sides.

Step 4: Write the resulting equation:

Al + CuCl₂→ AlCl₃ + Cu

Step 5: Now check whether the equation is balanced or not by comparing the atoms

We find that the equation is not balanced yet. As the number of Cu and Al atoms are unequal on the two sides. First balance the Al atom.

Step 6: If we multiply 2 in the reactant (in Al), we will get the equal number of Al atoms on both sides.

Step 7: Write the resulting equation:

2Al + 3CuCl₂→ 2AlCl₃ + Cu

Step 8: Now check whether the equation is balanced or not by comparing the atoms.

Step 9: Write the resulting equation:

2Al + 3CuCl₂→ 2AlCl₃ + Cu

We find that the equation is not balanced yet. As the number of copper atoms is unequal on the two sides.

Step 10: If we multiply 3 in the product (in Cu), we will get the equal number of atoms as in reactant (in CuCl₂)

Step 11: Write the resulting equation:

2Al + 3CuCl₂→ 2AlCl₃ + 3Cu

We find that the equation is balanced now.

Step 12: Write down the final balanced equation:

2Al + 3CuCl₂→ 2AlCl₃ + 3Cu

1. (ii) No

2. (iv) All of the above

3. (i) 2Mg + O₂ \(\longrightarrow\)2MgO

4. (iv) All of the above

5. (ii) FALSE

1. (i) Hydrogen + Oxygen \(\longrightarrow\) Water

2. (iii) Both (i)  and (ii)

3. (ii) FALSE

4. (iv) Magnesium Oxide

5. (ii) Arrowhead

Reactions in which heat energy is absorbed by the reactants are endothermic reactions.

A complete chemical equation represents the reactants, products, and their physical state.

A combination reaction or synthesis is a reaction in which two or more substances combine to form a single substance.

i. In earlier days, very few elements were known. They were classified as metals and non-metals on the basis of their properties. 

ii. Later, some more elements were discovered which showed the properties of both metals and non-metals. Thus, it became difficult to place them in the group of metals or non-metals.

1. Reactants are converted into products. 

2. Mass is conserved. 

3. Atoms are conserved. 

4. The properties and compositions of the products of a chemical reaction are different from those of its reactants. 

5. Generally, energy is either absorbed or evolved.

1. The use of strong acid and strong base in a chemical reaction increases the rate of reaction.

2. In a chemical reaction, if the smaller size of the reactant particles, the concentrated solution, high temperature and use of catalyst increases the rate of chemical reaction.

3. The rate of chemical reaction is important with respect to environment.

4. If the rate of chemimal reaction is fast it is profitable for the chemical factories.

5. The ozone layer in the earth’s atmosphere protects the life of earth from the ultraviolet radiation of the sun. The process of depletion or maintenance of this layer depends upon the rate of production or destruction of ozone molecules.

The properties which show gradual variation in a group and in a period and they repeat themselves after a certain interval of atomic number are called periodic properties.

Reproduction helps to increase their number and continue their existence.

Given \(\frac{x}{y} = \frac{3}{4},\)\(\frac{y}{z} = \frac{7}{9}\)

Given sum of their squares = 900 

(3x)² + (4x)²= 900 

9x² + 16x² = 900 

25x² = 900 

⇒ x² = \(\frac{900}{25}\) = 36 ⇒ x = 6 

∴ The numbers are 3(6) and 4(6) = 18 and 24

Let the two numbers are 6x and 7x

i.e., (7x)² – (6x)²= 117 

49x² – 36x²= 117 

13x² = 117 

⇒ x = 3 

∴ The numbers are 3(6) and 3(7) = 18 and 21.

Let their monthly incomes are 3x and 4x and their expenditure are 

3x – 2000 and 4x – 2000 

Given difference of their squares is

\(\frac{3x - 2000}{4x - 2000}\) = \(\frac{1}{2}\)

6x – 4000 = 4x – 2000 

⇒ 2x = 2000 ⇒ x = 1000 

The monthly income of A = 3x = 3 × 1000 = 3000 

The monthly income of B = 4x = 4 x 1000 = 4000

Given that the pocket money of Ravi and Sanjeev

Are in the ratio 5:7

Thus, the pocket money of ravi is 5k and that of

Sanjeev is 7k

Also given that the expenditure of ravi and Sanjeev

Are in the ratio 3:5

Thus, the expenditure of ravi is 3m and that of

Sanjeev is 5m

And each of them saves Rs. 80

⟹ 5k – 3m = 80 ….. (1)

7k – 5m = 80 …….. (2)

Solving equations (1) and (2), We have,

K = 40, m = 40

Hence the monthly pocket money of Ravi is Rs. 200

And that of Sanjeev is Rs. 280

Answer is (C) |(k,0,0),(0,k,0),(0,0,k)|

Having additional information on the Class 10 Science MCQ Question of Sources of Energy varying trouble will support your certainty and you can compose the assessment without fear. Practice is the solitary key for success in the CBSE Exams. You can begin practice with MCQ Question for class 10 with Answers for Board Exams.

Practice Class 10 Science MCQ Questions of Source of Energy

1. An ideal source of energy should have

(a) higher calorific value
(b) easy transportability
(c) easy accessibility
(d) All of these

2. Select the important factor for the site selection of a thermal power plant.

(a) Distance from the populated area
(b) Availability of fuel
(c) Availability’ of water
(d) Cost of plant

3. Hydropower plant are located in the

(a) desert area
(b) plane area
(c) hilly terrains
(d) none-of above

4. Coke is more valuable when used:

(a) As a fuel for industrial boilers
(b) As an oxidizing agent
(c) As a reducing agent
(d) As a fuel in domestic ovens

5. In order to make efficient solar cooker, the cover of cooker box should be made of:

(a) Transparent plastic sheet
(b) Shining aluminium sheet
(c) Butter paper sheet
(d) Transparent glass

6. Which of the followings is not a fossil fuel?

(a) Coal
(b) Petroleum
(c) Natural gas
(d) Nuclear fuel

7. The rise of sea-water during high tide is caused by the gravitational pull of the:

(a) Sun
(b) Earth
(c) Moon
(d) Mars

8. The disposal of wastes produced in a nuclear power plant is a big problem because it is:

(a) Highly radioactive
(b) Highly inflammable
(c) Extremely foul smelling
(d) Too heavy

9. The energy efficient device for producing light is:

(a) DLF
(b) CFL
(c) FCL
(d) LPG

10. Biogas is a better fuel than animal dung cake because

(a) biogas has lower calorific value.
(b) animal dung cake has high calorific value
(c) biogas bums smoke and leaves no residue
(d) biogas is used as a fuel for cooking only whereas dung cake can be used for cooking, illuminant the lanterns.

11. Wind is caused due to

(a) uneven heating of earth’s surface
(b) rotation of earth
(c) local conditions
(d) All of these

12. Solar cells are made of

(a) germanium
(b) silicon
(c) silver
(d) aluminium

13. Which one of the following is a renewable energy source?

(a) Coal
(b) Petroleum
(c) Natural gas
(d) Wind energy

14. A good source of energy is a given small amount of energy:

(a) Gives small amount of energy
(b) It cannot be stored easily
(c) It should be costly
(d) It should be easily accessible

15. Natural gas is better fossil fuel because:

(a) It is formed by decomposition of plants and animals
(b) It is found in gas form
(c) It is costly
(d) It is smokeless and no ash is left

16. Hydro power plants generate electricity from:

(a) a liquid
(b) by hot liquid
(c) by steam
(d) by potential energy of water

17. Ocean thermal energy is due to

(a) energy stored by waves in the ocean
(b) temperature difference at different levels in the ocean
(c) pressure difference at different levels in the ocean
(d) tides arising out in the ocean

18. The main constituent of biogas is

(a) methane
(b) carbon dioxide
(c) hydrogen
(d) hydrogen sulphide

19. Choose the correct statement.

(a) Sun is considered as an inexhaustible source of energy
(b) There is infinite storage of fossil fuel inside the Earth
(c) Hydro and wind energy plants are non-polluting sources of energy
(d) Waste from a nuclear power plant can be easily disposed off

20. Which of the following is the ultimate source of energy for us?

(a) LPG
(b) Nuclear
(c) Solar
(d) CNG

Answer Key

1. (d) All of these

Explanation: These are the characterises of ideal source of energy.

2. (c) Availability of water

Explanation: Water is required to produce steam. Thermal power plants are setup near the coal field and transmission of electricity is easy than transporting fuel.

3. (c) hilly terrains

Explanation: Hydroelectric power plant are generally located in high hilly areas where dam can easily be built and large reservoir for storage of water can be obtained.

4. (c) As a reducing agent

5. (d) Transparent glass

6. (d) Nuclear fuel

7. (c) Moon

8. (a) Highly radioactive

9. (b) CFL

10. (c) biogas bums smoke and leaves no residue

Explanation: Biogas has high calorific value and leave no residue, no smoke after burning and can be used for domestic purpose, running engines and in gas lanterns for illumination.

11. (d) All of these

Explanation: All are the factors that responsible for the blowing of wind.

12. (b) silicon

Explanation: Special grade silicon is used for making solar cells.

13. (d) Wind energy

14.(d) It should be easily accessible

15. (d) It is smokeless and no ash is left

16. (d) by potential energy of water

17. (b) temperature difference at different levels in the ocean

18. (a) methane

19. (a) Sun is considered as an inexhaustible source of energy

20. (c) Solar

Click here to practice more MCQ Questions from Chapter Sources of energy Class 10 Science

Given: 

Side of the equilateral triangle = 10cm 

Thus we have:

Area of the equilateral triangle = \(\frac{\sqrt{3}}{4}\) side²

= \(\frac{\sqrt{3}}4{}\times 10\times 10\)

= 25 x 1.732

= 43.3 cm²

30 x 6 + (5 – 2)

 = 30 x 6 – 3 

= 30 x 2 

= 60

B) 154 sq.cm

Correct option is  B) 2πr

19 – (1 + 5) – 3 

= 19 – 6 – 3 

= 19 – 9 

= 10

Area = \(\frac12\) x base x height 

Area of an equilateral Δ = \(\frac{\sqrt3}{4}\) × side² 

Area of a triangle with three sides given = \(\sqrt{s(s-a)(s-b)(s-c)}\) 

where s = \(\frac{a+b+c}{2}\) and a, b, c are the three sides.

The correct answer is (b) increases

The mean free path of a gas molecule depends upon the number of molecules per unit volume of the gas and molecular diameter.

 (d) kinetic energy.

The reagent used to convert Nitromethane to N – methyl hydroxylamine is Zn/NH₄CI.

(c) (iii) only

(c) Suiphanilic acid