NCERT Solutions

Exercise 14.5 1. Show that the statement “If is a real number such that then is 0” is true by (i) direct method (ii) method of contradiction (iii) method of contrapositive. Ans. The given compound statement is of the form “if then ”. R such that (i) Direct method: If we assume that is true … Read more

THE p -BLOCK ELEMENTS  1. Discuss the pattern of variation in the oxidation states of (i) B to Tl and (ii) C to Pb. 2. How can you explain higher stability of as compared to? 3. Why does boron trifluoride behave as a Lewis acid? 4. Consider the compounds,. How will they behave with water? … Read more

Miscellaneous Exercise 1. Write the negation of the following statements: (i) For every positive real number , the number is also positive. (ii) All cats scratch. (iii) For every real number , either or (iv) There exists a number such that Ans. (i) There exists a positive real number such that is not positive. (ii) … Read more

21.Discuss the chemistry of Lassaigne’s test. 22. Differentiate between the principle of estimation of nitrogen in an organic compound by (i) Dumas method and (ii) Kjeldahl’s method. 23. Discuss the principle of estimation of halogens, sulphur and phosphorus present in an organic compound. 24. Explain the principle of paper chromatography. 25. Why is nitric acid … Read more

Exercise 15.1 Find the mean deviation about the mean for the data in Exercises 1 and 2. 1. 4, 7, 8, 9, 10, 12, 13, 17 Ans. Mean of the given data Mean deviation about mean = = = 3 2. 38, 70, 48, 40, 42, 55, 63, 46, 54, 44 Ans. Mean of the … Read more

ORGANIC CHEMISTRY – SOME BASIC PRINCIPLES AND TECHNIQUES  1. What are hybridisation states of each carbon atom in the following compounds? 2. Indicate the bonds in the following molecules: 3. Write bond line formulas for: Isopropyl alcohol, 2,3-Dimethyl butanal, Heptan-4-one. 4. Give the IUPAC names of the following compounds: (a) (b) (c) (d) (e) (f) … Read more

Exercise 15.2 Find the mean and variance for each of the data in Exercises 1 to 5. 1. 6, 7, 10, 12, 13, 4, 8, 12 Ans. Given: = 6, 7, 10, 12, 13, 4, 8, 12 = 6 + 7 + 10 + 12 + 13 + 4 + 8 + 12 = 72 … Read more

Exercise 4.1 Prove the following by using the principle of mathematical induction for all N: 1. Ans. Let For 1 = 1 is true. Now, let be true for ……….(i) For [Using eq. (i)] is true. Therefore, is true. is true. Hence by Principle of Mathematical Induction, is true for all N. 2. Ans. Let … Read more

Miscellaneous Exercise 1. Find and in the expansion of if the first three terms of the expansion are 729, 7290 and 30375 respectively. Ans. Given: …..(i) …..(ii) And …..(iii) Multiplying eq. (i) and eq. (iii), …..(iv) Squaring both sides in eq. (ii), …..(v) Dividing eq. (iv) by eq. (v), From eq. (i), And From eq. … Read more

Miscellaneous Exercise 1. In a parabolic reflector is 20 cm in diameter and 5 cm deep, find the focus. Ans. A parabolic reflector with diameter PR = 20 cm and OQ = 5 cm Vertex of parabola is (0, 0) Let focus of the parabola be Now, PR = 20 cm PQ = 10 cm … Read more