Lesson Archives

  1. Page No 82: Question 1: What is meant by modification of root? What type of modification of root is found in the (a) Banyan tree (b) Turnip (c) Mangrove trees Answer: Primarily, there are two types of root systems found in plants, namely the tap root system and fibrous root system. The main function of the roots is […]
  2. Page No 62: Question 1: What are the difficulties that you would face in classification of animals, if common fundamental features are not taken into account? Answer: For the classification of living organisms, common fundamental characteristics are considered. If we consider specific characteristics, then each organism will be placed in a separate group and the […]
  3. Page No 44: Question 1: What is the basis of classification of algae? Answer: Algae are classified into three main classes – Chlorophyceae, Phaeophyceae, and Rhodophyceae. These divisions are based on the following factors: (a) Major photosynthetic pigments present (b) Form of stored food (c) Cell wall composition (d) Number of flagella and position of […]
  4. Page No 28: Question 1: Discuss how classification systems have undergone several changes over a period of time? Answer: The classification systems have undergone several changes with time. The first attempt of classification was made by Aristotle. He classified plants as herbs, shrubs, and trees. Animals, on the other hand, were classified on the basis […]
  5. Page No 15: Question 1: Why are living organisms classified? Answer: A large variety of plants, animals, and microbes are found on earth. All these living organisms differ in size, shape, colour, habitat, and many other characteristics. As there are millions of living organisms on earth, studying each of them is impossible. Therefore, scientists have […]
  6. 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 […]
  7. 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 […]
  8. 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 […]
  9. 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 […]
  10. 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 […]