NCERT Solutions

20. What happens when (a) Borax is heated strongly, (b) Boric acid is added to water, (c) Aluminium is treated with dilute NaOH, (d) is reacted with ammonia? 21. Explain the following reactions (a) Silicon is heated with methyl chloride at high temperature in the presence of copper; (b) Silicon dioxide is treated with hydrogen … Read more

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

Miscellaneous Exercise Prove that: 1. Ans. L.H.S. = = = = = = 0 = R.H.S. 2. Ans. L.H.S. = = = = = 0 = R.H.S. 3. Ans. L.H.S. = = = = = = R.H.S. 4. Ans. L.H.S. = = = = = = R.H.S. 5. Ans. L.H.S. = = = = = … Read more

Exercise 8.2 Find the coefficient of: 1. in Ans. General form of the expansion is ………(i) Putting in eq. (i), Therefore, coefficient of on the expansion is = 1512. 2. in Ans. General form of the expansion is ………(i) Putting in eq. (i), Therefore, coefficient of on the expansion is = Write the general term … Read more

Exercise 11.4 In each of the Exercises 1 to 6, find the coordinates of the foci, and the vertices, the eccentricity and the length of the latus rectum of the hyperbolas. 1. Ans. Given: Equation of hyperbola in the form Since, the foci and vertices of the hyperbola lies on axis. and Coordinates of foci … Read more