Exercise : Solutions of Questions on Page Number : 361 Q1 :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 in benzene are sp2 hybridised. Q2 :Indicate the ÃÆ’ and À bonds in the following molecules: C6H6,…
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Exercise : Solutions of Questions on Page Number : 323 Q1 :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 which practically show the +3 oxidation state. The remaining elements, i.e., Ga, In, Tl, show both the +1 and +3 oxidation states. On moving down the group, the +1 state becomes more stable. For example,…
Exercise : Solutions of Questions on Page Number : 305 Q1 :Explain why is sodium less reactive than potassium? Answer : In alkali metals, on moving down the group, the atomic size increases and the effective nuclear charge decreases. Because of these factors, the outermost electron in potassium can be lost easily as compared to sodium. Hence, potassium is more reactive than sodium. Q2 :Compare the alkali metals and alkaline earth metals with respect to (i) ionization enthalpy (ii) basicity of oxides and (iii) solubility of hydroxides. Answer : Alkali metals Alkaline earth metals (i) Ionization enthalpy: These have lowest…
Exercise : Solutions of Questions on Page Number : 288 Q1 :Justify the position of hydrogen in the periodic table on the basis of its electronicconfiguration. 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 both alkali metals and halogens. Resemblance with alkali metals: 1. Like alkali metals, hydrogen contains one valence electron in its valency shell. H : 1s1 Li : [He] 2s1 Hence, it can lose one electron to form a…
Exercise : Solutions of Questions on Page Number : 272 Q1 :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)NaH2PO4 Let the oxidation number of P be x. We know that, Oxidation number of Na = +1 Oxidation number of H = +1 Oxidation number of O = -2 Then, we have Hence, the oxidation number of P is +5. (b)NaHSO4 Then, we have Hence, the oxidation number of S is + 6. (c)H4P2O7 Then, we…
Exercise : Solutions of Questions on Page Number : 224 Q1 :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 equilibrium is restored finally and what will be the final vapour pressure? Answer : (a) If the volume of the container is suddenly increased, then the vapour pressure would decrease initially. This is because the amount of vapour remains…
Exercise : Solutions of Questions on Page Number : 182 Q1 :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 of a path. Functions like p, V, Tetc. depend only on the state of a system and not on the path. Hence, alternative (ii) is correct. Q2 :For the process to occur under adiabatic conditions, the correct condition…
Exercise : Solutions of Questions on Page Number : 152 Q1 :What will be the minimum pressure required to compress 500 dm3 of air at 1 bar to 200 dm3 at 30°C? Answer : Given, Initial pressure, p1 = 1 bar Initial volume, V1 = 500 dm3 Final volume, V2 = 200 dm3 Since the temperature remains constant, the final pressure (p2) can be calculated using Boyle’s law. According to Boyle’s law, Therefore, the minimum pressure required is 2.5 bar. Q2 :A vessel of 120 mL capacity contains a certain amount of gas at 35 °C and 1.2 bar pressure.…
Exercise : Solutions of Questions on Page Number : 129 Q1 :Explain the formation of a chemical bond. Answer : A chemical bond is defined as an attractive force that holds the constituents (atoms, ions etc.) together in a chemical species. Various theories have been suggested for the formation of chemical bonds such as the electronic theory, valence shell electron pair repulsion theory, valence bond theory, and molecular orbital theory. A chemical bond formation is attributed to the tendency of a system to attain stability. It was observed that the inertness of noble gases was because of their fully filled…
Exercise : Solutions of Questions on Page Number : 92 Q1 :What is the basic theme of organisation in the periodic table? Answer : The basic theme of organisation of elements in the periodic table is to classify the elements in periods and groups according to their properties. This arrangement makes the study of elements and their compounds simple and systematic. In the periodic table, elements with similar properties are placed in the same group. Q2 :Which important property did Mendeleev use to classify the elements in his periodic table and did he stick to that? Answer : Mendeleev arranged…