Class 08 NCERT Solutions

Science Chapter-13: Sound

Select the correct answer from the following:

Que.1.The propagation of sound takes place through

(i) solids only (ii) liquids only (iii) gases only (iv) solids, liquids and gases.

Science Chapter-15: Some Natural Phenomena

Q.1. Identify the one which does not charge by friction that easily?

(i) An inflamed balloon

(ii) A woolen cloth

(iii) A plastic scale

(iv) A copper rod

Science Chapter-02: Microorganisms: Friend And Foe

Q.1. Fill in the blanks:

(i) ___________ is used to see microorganisms.

(ii) ___________ causes cholera.

(iii)___________ is used to produce alcohol.

(iv)___________ is fixed directly from air to enhance the soil fertility by blue green algae.

Science Chapter-06: Combustion and Flame

1. What are the conditions under which a combustion can take place?

Science Chapter-04: Materials : Metals and Non-Metals

Question-1

Which of the following can be beaten into thin sheets?

(i) Phosphorus (ii) oxygen (iii) zinc (iv) sulphur

Science Chapter-08: Cell: Structure and Functions

1. Indicate whether the following statements are True or False.

a) Unicellular organisms have a one-celled body.

b) Muscle cells are branched.

c) The basic living unit of an organism is an organ.

d) Amoeba has irregular shape.

Science Chapter-03: Synthetic Fibres and Plastics

Question-1

Explain the reason why some of the fibres are called synthetic.

Science Chapter-05: Coal and Petroleum

Question 1:

Compressed Natural Gas (CNG) and Liquefied Petroleum Gas (LPG) are used as fuels. What are its advantages?

Science Chapter-01: Crop Production and Management

1. FILL THE CORRECT WORDS IN THE GIVEN BLANKS.

(a) The cultivation of a single variety of plants at a place on a big scale in terms of area are known as ________________.

(b) The seeds that are damaged will _________on upper portion of the water.

(c) Sufficient ______,________ and ____________in the soil is required for the growth of a crop.

(d) __________________of the soil is the first step before growing crops.

Science Chapter-14: Chemical Effects of Electric Current

1. Complete the following sentence.

(a) _______, _______ and _______ are the liquids that conduct electricity.

(b) _______ is the effect generated when an electric current is passed through a solution.

(c)_______ is known as the process for depositing a layer of any metal on another material by the means of Electricity.

Science Chapter-09: Reproduction in Animals

1) What is the importance of reproduction in organisms?

Solution:

• Reproduction is termed to be a biological process in which organisms give birth to their off springs.
• It helps in maintaining the continuity of particular race and helps in increasing the population of the species.
• Reproduction is meant for survival of all living things.

Science Chapter-07: Conservation of Plants and Animals

1. Fill in the blanks:

(a) _______ is a place where animals are protected in their own natural habitat.

(b) Species found only in a particular area are known as _______.

(c) Migratory birds fly to faraway places because of _______ changes.

Science Chapter-10: Reaching the Age of Adolescence

Question-1

Which chemical substance is secreted by the endocrine glands which are responsible for the changes taking place in the body?

Science Chapter-12: Friction

Question-1

Fill in the blanks with the appropriate words.

a) It is the________of the surface on which the friction depends.

b) Sliding friction is_______compared to the static friction.

c) _________is produced by the friction.

Science Chapter-18: Pollution of Air and Water

Question-1

State the different ways in which water is contaminated.

Science Chapter-11: Force and Pressure

Question-1

In which situations, do you need to pull or push to change the state of motion of an object? Give two examples.

Science Chapter-17: Stars and the Solar System

Question 1:

From the following pick out, which is not the member of the solar system?

a) A satellite

b) A comet

c) An asteroid

d) A constellation

Science Chapter-16: Light

Q1)

Imagine a person is in a dark room, will he be able to see any object which is kept inside the room and any other object which is kept out of the room? Elaborate.

Maths Chapter-02: Linear Equations in One Variable

Exercise 1

Question-1

Solve the linear equation $$\frac{x}{2}-\frac{1}{5}=\frac{x}{3}+\frac{1}{4}$$

Maths Chapter-01: Rational Numbers

1. Using appropriate properties find the value of $$\frac{-2}{3}\times \frac{3}{5}+\frac{5}{2}-\frac{3}{5}\times \frac{1}{6}$$

Maths Chapter-09: Algebraic Expressions and Identities

Q.1. Identify the terms and their coefficients for each of the following expressions.

(I) 5abc2 – 3cb

Maths Chapter-08: Comparing Quantities

Q1. Calculate the ratio for the following:

(i) The scooter runs with a speed of 30 km/hour and the cycle runs with a speed of 60 km/ hour.

Maths Chapter-06: Squares and Square Roots

Question-1) Determine which digit will be at the unit’s place in the squares of the numbers given below:

1. 36
2. 273
3. 798
4. 3864
5. 58637
6. 63545
7. 16542
8. 45640
9. 98231
10. 89999

Maths Chapter-16: Playing with Numbers

Exercise 16.1

1. In the given addition, find the value of the letters and give reason.

Maths Chapter-14: Factorisation

Ex.14.1

Question1. Calculate the common factors of the following:

( i )16a and 28 ( i i )26x and 13ya

( iii )20pq, 30rp and 20pqr ( iv )12a3y2 and 5a2y3z2

( v ) 8abc and 18ab2 ( vi )6pqr, 24pq2 and 12p2q

Exercise 3.1

Q1) Given below are some shapes.

Identify the below diagrams based on the following category

(a) Concave polygon (b) Simple curve (c)Convex polygon

(d)Simple closed curve (e) Polygon

Maths Chapter-12: Exponents and Powers

Exercise-12.1

Q.1. (i)$$4^{-3}$$

(ii)$$(-5)^{-5}$$

(iii)$$(\frac{1}{2})^{-4}$$

Maths Chapter-07: Cubes and Cube Roots

Exercise 7.1

Q1:

Mention the numbers that are not perfect cubes.

Maths Chapter-11: Mensuration

Exercise 11.1

1. A rectangle and a square field with given measurements have same perimeter is given below in the figure. Which of the following has larger area?

Maths Chapter-13: Direct and Inverse Proportions

Exercise 13.1

Q1: Following are the car parking charges near railway station according to the hours:

Maths Chapter-05: Data Handling

Exercise 5.1

1. For which of these would you use a histogram to show the data:

(a) The number of letters for different areas in a postman’s bag.

(b) The height of competitors in an athletics meet.

(c) The number cassettes produced by 5 companies.

Maths Chapter-10: Visualising Solid Shapes

Exercise 10.1

Question 1:

Given below are solids, and their compared views. Match them by comparing them with their top views and front views. For the example default: The first is done for you:

Maths Chapter-04: Practical Geometry

Exercise 4.1

Question 1:

(b) When was the temperature of the patient $$36.5^{\circ}$$?