Lesson Archives

  1. Page No 8: Question 1: Mark the following statements as true or false. (i) Statistics can only deal with quantitative data. (ii) Statistics solves economic problems. (iii) Statistics is of no use to Economics without data. Answer: (i) Statistics can only deal with quantitative data. False Statistics deals with both quantitative data as well as […]
  2. Page No 413: Question 14.1: Define environmental chemistry. Answer: Environmental chemistry is the study of chemical and biochemical processes occurring in nature. It deals with the study of origin, transport, reaction, effects, and fates of various chemical species in the environment. Question 14.2: Explain tropospheric pollution in 100 words. Answer: Tropospheric pollution arises due to […]
  3. Page No 396: Question 13.1: How do you account for the formation of ethane during chlorination of methane? Answer: Chlorination of methane proceeds via a free radical chain mechanism. The whole reaction takes place in the given three steps. Step 1: Initiation: The reaction begins with the homolytic cleavage of Cl – Cl bond as: Step […]
  4. Page No 361: Question 12.1: What are hybridisation states of each carbon atom in the following compounds? CH2=C=O, CH3CH=CH2, (CH3)2CO, CH2=CHCN, C6H6 Answer: (i)  C–1 is sp2 hybridised. C–2 is sp hybridised. (ii)  C–1 is sp3 hybridised. C–2 is sp2 hybridised. C–3 is sp2 hybridised. (iii) C–1 and C–3 are sp3 hybridised. C–2 is sp2 hybridised. (iv)  C–1 is sp2 hybridised. C–2 is sp2 hybridised. C–3 is sp hybridised. (v) C6H6 All the 6 carbon atoms […]
  5. Page No 323: Question 11.1: Discuss the pattern of variation in the oxidation states of (i) B to Tl and (ii) C to Pb. Answer: (i) B to Tl The electric configuration of group 13 elements is ns2 np1. Therefore, the most common oxidation state exhibited by them should be +3. However, it is only boron and aluminium […]
  6. Page No 305: Question 10.1: What are the common physical and chemical features of alkali metals? Answer: Physical properties of alkali metals are as follows. (1) They are quite soft and can be cut easily. Sodium metal can be easily cut using a knife. (2) They are light coloured and are mostly silvery white in appearance. (3) They […]
  7. Page No 288: Question 9.1: Justify the position of hydrogen in the periodic table on the basis of its electronic configuration. Answer: Hydrogen is the first element of the periodic table. Its electronic configuration is [1s1]. Due to the presence of only one electron in its 1s shell, hydrogen exhibits a dual behaviour, i.e., it resembles […]
  8. Page No 272: Question 8.1: Assign oxidation numbers to the underlined elements in each of the following species: (a) NaH2PO4 (b) NaHSO4 (c) H4P2O7 (d) K2MnO4 (e) CaO2 (f) NaBH4 (g) H2S2O7 (h) KAl(SO4)2.12 H2O Answer: (a)  Let the oxidation number of P be x. We know that, Oxidation number of Na = +1 Oxidation number of H = +1 Oxidation number […]
  9. Page No 224: Question 7.1: A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased. a) What is the initial effect of the change on vapour pressure? b) How do rates of evaporation and condensation change initially? c) What happens when […]
  10. Page No 182: Question 6.1: Choose the correct answer. A thermodynamic state function is a quantity (i) used to determine heat changes (ii) whose value is independent of path (iii) used to determine pressure volume work (iv) whose value depends on temperature only. Answer: A thermodynamic state function is a quantity whose value is independent […]