September Test 2024 Chemistry-XI SET 2

 

September Test 2024

Chemistry-XI

Time Allowed: 3 hrs.

Maximum Marks: 70

Note:

• Q.No. 1 has 20 parts carrying 1 mark each
• Q.No. 2 to 15 carry 2 marks each
• Q.No. 16 to 19 carry 3 marks each
• Q.No. 20 to 21 carry 5 marks each

SECTION – A (Each carry 1 mark)

1. The number of molecules in one mole of methane CH₄ is:
   • (a) 3.0 x 10²³
   • (b) 6.022 x 10²³
   • (c) 16/6.022 x 10²³
   • (d) 16/3 x 10²³
2. Number of significant figures in 234.000 is:
   • (a) 3
   • (b) 6
   • (c) 5
   • (d) 4
3. In three moles of ethane C₂H₆, number of moles of carbon atoms are:
   • (a) 18
   • (b) 6
   • (c) 10
   • (d) 2
4. Which of the following is dependent on temperature?
   • (a) Molarity
   • (b) Molality
   • (c) Mole fraction
   • (d) Mass percentage
5. A p-orbital can accommodate up to:
   • (a) 4 electrons
   • (b) 6 electrons
   • (c) 2 electrons with parallel spins
   • (d) 2 electrons with opposite spin
6. Two electrons occupying the same orbital are distinguished by:
   • (a) Spin quantum number
   • (b) Azimuthal quantum number
   • (c) Magnetic quantum number
   • (d) Principal quantum number
7. Elements tend to get 8 electrons in the outermost shell, this is known as:
   • (a) Doublet rule
   • (b) Octet rule
   • (c) Triplet rule
   • (d) Quadrant rule
8. According to Bohr theory, the angular momentum of an electron in the 4th orbit is:
   • (a) 20h/π
   • (b) 10h/π
   • (c) 2h/π
   • (d) h/π
9. The wavelength of a 100g particle moving with a velocity of 100ms^-1 is (h=6.626 x 10^-34 kg m² s^-1):
   • (a) 6.626 x 10^-10 m
   • (b) 6.626 x 10² m
   • (c) 6.626 x 10^-35 m
   • (d) 6.022 x 10^-23 m
10. Predict the hybridisation of NH₃ molecule:
    • (a) sp³d²
    • (b) sp
    • (c) sp³
    • (d) sp³d³

Comprehension

These are the elements of group 3 to 12 in the centre of the periodic table. These are characterised by the filling of inner d-orbitals by electrons and are therefore referred to as d-block elements. These elements have the general outer electronic configuration (n-1)d^1-10 ns^1-2. They are all metals. They mostly form coloured ions, exhibit variable valence (oxidation states), show paramagnetism, and are often used as catalysts. However, Zn, Cd, and Hg, which have the electronic configuration (n-1)d¹⁰ ns², do not show most of the properties of transition elements.

11. What are transition elements?
12. Write the electronic configuration of d-block elements?
13. What is paramagnetic character?
14. Why are Zn, Cd, and Hg not regarded as transition elements?
15. Write the difference between s-block and d-block elements.

True / False

16. Equal volumes of different gases under similar conditions of temperature and pressure contain equal numbers of molecules. (True/False)
17. The designation of orbital n=4 and l=0 is 4s. (True/False)
18. No bond is purely ionic or purely covalent. (True/False)
19. The first element of each group of representative elements shows anomalous behaviour. (True/False)
20. Group 17 elements are called noble gases. (True/False)

SECTION – B (Each carry 2 marks)

1. Define empirical formula and molecular formula.
2. Calculate the number of atoms in (i) 52 moles of Ar, (ii) 52 u of He. Or, how much copper can be obtained from 100 grams of CuSO₄? (Atomic mass of copper = 63.5 g/mol)
3. Calculate the mass percent of sodium and oxygen in Na₂SO₄.
4. Give the difference between orbit and orbital.
5. Discuss and draw the shape of p-orbitals.
6. Noble gases have the highest ionization energy in their respective periods. Why?
7. Write the difference between electron gain enthalpy and electronegativity.
8. Give the difference between sigma bond and pi bond.
9. On the basis of VSEPR theory, discuss the shape of NH₃.
10. How many electrons in an atom may have the following quantum numbers:
    • (a) n=4, m_s= -1/2
    • (b) n=3, l=0
11. Calculate the wavelength and frequency of a light wave whose period is 2.0 x 10^-10 s.
12. What do you understand by isoelectronic species? Name a species that will be isoelectronic with F^- and Mg²⁺.
13. What is hydrogen bonding? What are the conditions for hydrogen bonding?
14. Calculate the formal charge on each oxygen atom of ozone.

SECTION – C (Each carry 3 marks)

1. Define atomic mass of an element, one atomic mass unit, and parts per million.
2. Write down the electronic configuration of Na⁺, F^-, and Cr.
3. A microscope using suitable photons is employed to locate an electron in an atom within a distance of 0.1 Å. What is the uncertainty involved in measurement of its velocity? (mass of electron = 9.1 x 10^-31 kg)
   OR
   The energy associated with the first orbit in the hydrogen atom is -2.18 x 10^-18 J atom^-1. What is the energy associated with the fifth orbit?
4. • (i) What is the total number of sigma and pi bonds in C₂H₂?
   • (ii) Which hybrid orbitals are used by carbon atoms in CH₃-CH=CH₂?

SECTION – D (Each carry 5 marks)

1. Draw the molecular orbital diagram of N₂. Explain bond order and magnetic property.
   OR
   What is meant by hybridisation of atomic orbitals? Describe the shape of sp, sp², and sp³ hybrid orbitals.
2. • (i) Write the difference between molarity and molality.
   • (ii) State and explain the law of definite proportion.
   
   OR
   
   • (i) What is a limiting reagent? Calculate the amount of carbon dioxide that could be produced when 1 mole of carbon is burnt in air.
   • (ii) What will be the mass of one 12C atom in grams?