SCIENCE AND MATH CONCEPTS

Chemical Reactions and Equations Question-1 Which of the given statements about the reaction below are incorrect? a. Lead is getting reduced b. Carbon dioxide is getting oxidised c. Carbon is getting oxidised d. Lead oxide is getting reduced (i) (a) and (b) (ii) (a) and (c) (iii) (a), (b) and (c) (iv) all Solution: (i) (a) and (b) Question-2 The above reaction is an example of a (i). Combination reaction (ii). Double displacement reaction (iii). Decomposition reaction (iv). Displacement reaction Solution: (iv) Displacement reaction Question-3 What happens when dilute hydrochloric acid is added to iron fillings? Tick the correct answer. a. Hydrogen gas and iron chloride are produced b. Chlorine gas and iron hydroxide are produced c. No reaction takes place d Iron salt and water are produced Solution: Hydrogen gas and iron chloride are produced Download NCERT Solutions for Class 10 Science Chapter 1 Chemical Reactions and Equations PDF Question-4

Constructions Ex 11.1 Question 1. Draw a line segment of length 7.6 cm and divide it in the ratio 5:8. Measure the two parts. Solution: Question 2. Construct a triangle of sides 4 cm, 5 cm and 6 cm and then a triangle similar to it whose sides are   of the corresponding sides of the first triangle. Solution: Question 3. Construct a triangle with sides 5 cm, 6 cm, and 7 cm and then another triangle whose sides are   of the corresponding sides of the first triangle. Solution: Question 4. Construct an isosceles triangle whose base is 8 cm and altitude 4 cm and then another triangle whose sides are 1  times the corresponding sides of the isosceles triangle. Solution: Question 5. Draw a triangle ABC with side BC = 6 cm, AB = 5 cm and ∠ABC = 60°. Then construct a triangle whose sides are   of the corresponding sides of the triangle ABC. Solution:   Question 6. Draw a triangle ABC with side BC = 7 cm, ∠B = 45°, ∠A = 105°. Then, construct a triangle whose sides are  time

Real Numbers Ex 1.1 Question 1. Use Euclid’s Division Algorithm to find the HCF of: (i) 135 and 225 (ii) 196 and 38220 (iii) 867 and 255 Solution: Question 2. Show that any positive odd integer is of the form 6q + 1, or 6q + 3, or 6q + 5, where q is some integer. Solution Question 3. An army contingent of 616 members is to march behind an army band of 32 members in a parade. The two groups are to march in the same number of columns. What is the maximum number of columns in which they can march? Solution: Question 4. Use Euclid’s division lemma to show that the square of any positive integer is either of the form 3m or 3m + 1 for some integer m. Solution: Question 5. Use Euclid’s Division Lemma to show that the cube of any positive integer is either of the form 9m, 9m + 1 or 9m + 8. Solution: Real Numbers Ex 1.2 Question 1. Express each number as a product of its prime factors: (i) 140 (ii) 156 (iii) 3825 (iv) 5005 (v) 7429 Solution: Qu