11th Chemistry

Chapter – 7 Definitions If S.I Unit 1. Assign oxidation number to the underlined elements in each of the following species: (a)\(\begin{array}{l}NaH_2\underline{P}O_4\end{array} \) (b)\(\begin{array}{l}NaH\underline{S}O_{4}\end{array} \) (c)\(\begin{array}{l}H_{4}\underline{P}_{2}O_{7}\end{array} \) (d)\(\begin{array}{l}K_{2}\underline{Mn}O_{4}\end{array} \) (e)\(\begin{array}{l}Ca\underline{O}_{2}\end{array} \) (f)\(\begin{array}{l}Na\underline{B}H_{4}\end{array} \) (g)\(\begin{array}{l}H_{2}\underline{S}_{2}O_{7}\end{array} \) (h)\(\begin{array}{l}KAl(\underline{S}O_{4})_{2}.12 H_{2}O\end{array} \) Answer: (a) \(\begin{array}{l}NaH_2\underline{P}O_4\end{array} \)Let x be the oxidation no. of P.Oxidation no. of Na = +1O xidation … Read more

Chapter – 6 Equilibrium Question 1. A liquid is in equilibrium with its vapours in a sealed container at a fixed temperature. The volume of the container is suddenly increased, (i) What is the initial effect of the change on the vapour pressure? (ii) How do the rates of evaporation and condensation change initially? (iii) … Read more

Chapter – 5 Thermodynamics Question 1. Choose the correct answer: A thermodynamic state junction 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: (ii) whose value is independent of path Question 2. For … Read more

Chapter – 4 Chemical Bonding And Molecular Structure 1. Explain the formation of a chemical bond. Solution : 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 … Read more

Chapter – 3 Classification of Elements and Periodicity in Properties 1. Explain why the electron gain enthalpy of fluorine is less negative than that of chlorine. Answer. This is due to the small size of the fluorine atom. As a result of the strong inter electronic repulsions in fluorine’s relatively small 2 p orbitals, the … Read more

Chapter 2 Structure of Atom 1. (i) Calculate the number of electrons which will together weigh one gram.(ii) Calculate the mass and charge of one mole of electrons. Solution : (i) Mass of one electron = 9.10939 × 10–31 kg Number of electrons that weigh 9.10939 × 10–31 kg = 1Number of electrons that will … Read more

Chapter 1 Some Basic Concepts of Chemistry 1. Calculate the molecular mass of the following : (i) H2O (ii) CO2 (iii) CH4 Solution : (i)CH4 :Molecular weight of methane, CH4= (1 x Atomic weight of carbon) + (4 x Atomic weight of hydrogen)= [1(12.011 u) +4 (1.008u)]= 12.011u + 4.032 u= 16.043 u (ii) H2O … Read more