Tiêu đề XI CHEMISTRY QP.pdf ✅

HALF YEARLY EXAMINATION 2023-24 SUBJECT: CHEMISTRY THEORY (043) DURATION: 3 Hrs MAXIMUM MARKS: 70 General Instructions: Read the following instructions carefully. a) There are 33 questions in this question paper with internal choice. b) SECTION A consists of 12 multiple-choice questions carrying 1 mark each. c) SECTION B consists of 4 assertion reasons-based questions carrying 1 mark each. d) SECTION C consists of 5 very short answer questions carrying 2 marks each. e) SECTION D consists of 7 short answer questions carrying 3 marks each. f) SECTION E consists of 2 case- based questions carrying 4 marks each. f) SECTION F consists of 3 long answer questions carrying 5 marks each. g) All questions are compulsory. However, internal choice is given in question number 28 & 32. h) Use of log electronic gadgets and calculators are not allowed SECTION A The following questions are multiple-choice questions with one correct answer. Each question carries 1 mark. There is no internal choice in this section. 1. The total number of ions present in 111 g of CaCl2 is (a) One Mole (b) Two Mole (c) Three Mole (d) Four Mole 2. A measured temperature on Fahrenheit scale is 200F. What will this reading be on the Celsius Scale? (a) 40 0C (b) 94 0C (c) 93.3 0C (d) 30 0C 3. Which of the following pairs represents isobars? (a) 3He2 and 4He2 (b) 24Mg12 and 25Mg12 (c) 40K19 and 40Ca20 (d) 40K19 and 39K19 4. Principal, Azimuthal and magnetic quantum numbers are respectively related to: (a) Size, shape and orientation (b) Shape, size and orientation (c) Size, orientation and shape (d) None of the above 5. The electronic configuration of chromium (Z=24) is: (a) [Ne] 3s2 3p6 3d4 4s2
(b) [Ne] 3s2 3p6 3d5 4s1 (c) [Ne] 3s2 3p6 3d1 4s2 (d) [Ne] 3s2 3p6 4s2 4p4 6. The element with atomic number 26 will be found in group: (a) 2 (b) 8 (c) 6 (d) 10 7. The elements of group 17 are called———- (a) noble gases (b) chalcogens (c) halogens (d) alkali metals 8. The total number of sigma (s) and pi (p) bonds in ethene molecule is (a) 1 sigma (s) and 2 pi (p) bonds (b) 3 sigma (s) and 2 pi (p) bonds (c) 4 sigma (s) and 1 pi (p) bonds (d) 5 sigma (s) and 1 pi (p) bonds 9. The ion which is iso-electronic with CO is ————— (a) N2 + (b) O2 – (c) CN– (d) O2 + 10. In which of the following process, a maximum increase in entropy is observed. (a) Dissolution of Salt in Water (b) Condensation of Water (c) Sublimation of Naphthalene (d) Melting of Ice 11. Internal energy of a substance/system is (a) State function (b) Path function (c) Neither state function nor path function (d) Both state function as well as path function 12. In a group of the periodic table the Ionization enthalpies of the elements decreases from top to bottom because of ———- (a) increase in densities (b) decrease in chemical reactivities (c) increase in atomic sizes (d) decrease in electronegativities SECTION B (Assertion and Reason based Questions) Directions: Each of these questions contain two statements, Assertion and Reason. Each of these questions also has four alternative choices, only one of which is the correct answer. You have to select one of the codes (a), (b), (c) and (d) given below. (a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion. (c) Assertion is correct, reason is incorrect. (d) Assertion is incorrect, reason is correct. 13. Assertion: One atomic mass unit is defined as one twelfth of the mass of one carbon12 atoms. Reason: Carbon-14 isotope is the most abundant isotope of carbon and has been chosen as standard. 14. Assertion: According to Mendeleev, periodic properties of elements is a function of their atomic number. Reason: Atomic number is equal to the number of protons. 15. Assertion: Entropy of system increases for a spontaneous reaction. Reason: Enthalpy of reaction always decreases for spontaneous reaction. 16. Assertion: Shape of NH3 molecule is tetrahedral. Reason: In NH3 nitrogen is sp3 hybridized. SECTION C (Very Short Answer Type Questions) 17. What is the law of multiple proportion explain with one example? 18. (a) What is IUPAC name and symbol of atomic number 120? (b) Explain Diagonal relationship. 19. Among the elements B, Al, C and Si, (i) which element has the highest first ionisation enthalpy? (ii) which element has the most metallic character? Justify your answer in each case. 20. (a) What is First Law of Thermodynamics explain? (b) Calculate the work done a when an ideal gas expands from 2L to 4L isothermally into vacuum? 21. The enthalpy of atomisation for the reaction CH4(g)→ C(g) + 4H (g) is 1665 kJ mol–1 . What is the bond energy of C–H bond? SECTION D (Short Answer Type Questions) 22. A compound contains 4.07 % hydrogen, 24.27 % carbon and 71.65 % chlorine. Its molar mass is 98.96 what are its empirical and molecular formula? 23. If 4 g of NaOH dissolves in 36 g of H2O, calculate the mole fraction of each component in the solution. Also, determine the molarity of solution (specific gravity of solution is 1g ml-1 ) 24, i. How does metalic charecter change in a group? ii.Explain why cations are smaller and anions are larger in radii than their parent atom? 25. Indicate the number of unpaired electrons in: (a)P (b)Si (c)Cr (d)Fe (e)Kr (f) Cl (Atomic No, P =15 , Si=14 , Cr= 24 , Fe=26 , Kr=36 , Cl=17 )
26, (a) Why does nitrogen have higher ionisation energy than oxygen? (b) Why is the electron gain enthalpy of chlorine more negative than fluorine? (c) Why do noble gases have zero electron gain enthalpy values? 27. (a) AmongNH3 and NF3 which one has higher dipole moment and why ? (b) Why H2O is a liquid while H2S is a gas? 28. (a) Define lattice energy. (b) What is Born-Haber cycle and How does it helps in calculating the lattice energy? OR (a) What do you mean by heat capacity? (b) Derive the relation between Cp and CV? SECTION E (Case-based Answer Type Questions) 29, Read the following passage and answer the questions that follow: Orbitals are regions or spaces where there is a maximum probability of finding electrons. Qualitatively, these orbitals can be distinguished by their size, shape, and orientation. An orbital of small size means there is more chance of finding the electron near the nucleus. Shape and orientation mean the direction in which the probability of finding the electron is maximum. Atomic orbitals can be distinguished by quantum numbers. Each orbital is designated by three quantum numbers n, l, and ml (magnetic quantum number) which define energy, shape, and orientation but these are not sufficient to explain spectra of multi-electrons atoms. Spin quantum number (ms) determines the spin of electrons. Spin angular momentum of the electron has two orientations relative to the chosen axis which are distinguished by spin quantum numbers ms which can take values +1/2 and –1/2. (a) How many orbitals are associated with n = 3? (b) Describe the orbitals represented by (i) n = 2, l = 1 (ii) n = 4, l = 0. (c) How many electrons are possible in an orbital? (d) What is the shape of ‘s’ and ‘p’ orbitals? 30. In chemistry, orbital hybridisation (or hybridization) is the concept of mixing atomic orbitals to form new hybrid orbitals (with different energies, shapes, etc., than the component atomic orbitals) suitable for the pairing of electrons to form chemical bonds in valence bond theory. For example, in a carbon atom which forms four single bonds the valence-shell s orbital combines with three valence-shell p orbitals to form four equivalent sp3 mixtures in a tetrahedral arrangement around the carbon to bond to four different atoms. Hybrid orbitals are useful in the explanation of molecular geometry and atomic bonding properties and are symmetrically disposed in space. Usually hybrid orbitals are formed by mixing atomic orbitals of comparable