Saturday, 5 July 2014

Exercise 1.3 Real Numbers | CBSE Class 10th Mathematics | Solutions

Question 1. Prove that √5 is irrational.

Solution : Let us assume, to the contrary, that √5 is rational.
That is, we can find integers a and b (≠ 0) such that :
a
√5=
b
Suppose a and b have a common factor other than 1, then we can divide by the common factor, and assume that a and b are coprime.
So, b √5 = a⋅

Friday, 4 July 2014

Real Numbers - Exercise 1.2 | CBSE Class 10th Mathematics | Solutions

Question 1. Express each number as a product of its prime factors:
(i) 140   (ii) 156    (iii) 3825   (iv) 5005    (v) 7429


Solution (i) To express the given number 140 as product of its prime factors, we employ the division method as shown below :

2|140
2|70
5|35
7|7
|1

∴ 140 = 2×2×5×7
       = 22×5×7


Thursday, 3 July 2014

Real Numbers - Exercise 1.1 | CBSE Class 10th Mathematics | Solutions

Points to remember

  • An algorithm is a series of well defined steps which gives a procedure for solving a type of problem. The word algorithm comes from the name of the 9th century Persian mathematician al-Khwarizmi.
  • A lemma is a proven statement used for proving another statement.
  • Euclid’s Division Lemma : Given positive integers a and b, there exist unique integers q and r satisfying a = bq + r, 0 ≤ r < b.
  • Euclid’s division algorithm : Euclid’s division algorithm is a technique to compute the Highest Common Factor (HCF) of two given positive integers. This is based on Euclid’s division lemma. According to this, the HCF of any two positive integers c and d, with c > d, is obtained as follows:

Friday, 4 April 2014

CBSE Class 10th - Science | Solved Exercises

This post contains links to solutions of all chapters for NCERT textbook of Science for Class 10th under CBSE. Each link for the chapter provides solutions to questions given in its main exercises including multiple choice questions, numericals, activities and in-text questions given after a main section to check the under standing of  the topic by students .

Monday, 31 March 2014

CBSE Class 10th Science | Chapter 16. Management of Natural Resources | Solved Exercises

In Text Questions | Page 269 |Chapter 16. Management of Natural Resources | CBSE Class 10th Science |  

Question 1. What changes can you make in your habits to become more environment-friendly?

Answer. We can make certain positive changes in our habits to become more environment-friendly. We can follow the simple policy of the three R's i.e., Reduce, Reuse and Recycle
 Which simply means that for our living,

Saturday, 29 March 2014

CBSE Class 10th Science | Chapter 15. Our Environment | Solved Exercises

In Text Questions | Page 257 |Chapter 15. Our Environment | CBSE Class 10th Science

Question 1. Why are some substances biodegradable and some non-biodegradable?

Answer. Some substances can be acted upon by the micro organisms and broken down into simple substances. Such substances are called biodegradable.
Some substances are inert and cannot be acted upon by the microorganisms and do not breakdown into simple substances. Such substances are called non- biodegradable.

CBSE Class 10th Science | Chapter 14. Sources of Energy | Solved Exercises

Question 1. A solar water heater cannot be used to get hot water on
(a) a sunny day.
(b) a cloudy day.
(c) a hot day.
(d) a windy day.

Answer. (b) a cloudy day.

Monday, 24 March 2014

CBSE Class 10th Science | Chapter 13. Magnetic Effects of Electric Current | Solved Exercises

Question 1. Which of the following correctly describes the magnetic field near a long straight wire?
(a) The field consists of straight lines perpendicular to the wire.
(b) The field consists of straight lines parallel to the wire.
(c) The field consists of radial lines originating from the wire.
(d) The field consists of concentric circles centred on the wire.

Answer. (d) The field consists of concentric circles centred on the wire.

Tuesday, 4 March 2014

CBSE Class 10th Science | Chapter 12. Electricity | Solved Exercises

Question 1. A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R′, then the ratio R/R′ is –
(a) 1/25
(b) 1/5
(c) 5
(d) 25

Answer. (d) 25

Friday, 21 February 2014

CBSE Class IX (9th) Science | All Chapters Solved Exercises


 Solved Exercises : CBSE Class IX (9th) Science
Each link, as given below, provides solutions to questions given in  main exercises of the chapters,  including multiple choice questions, numericals, activities and In Text questions given after a main section to check the under standing of  the topic by students .