Date:_________ SUBJECT : CHEMISTRY (Q.

B) Time : 3 Hr
Marks: 70

SECTION A

Q.1. Multiple Choice Questions [1 mark Each]

(i) For pH > 7, then hydronium ion concentration would be __________.

(a) 10−7 M (b) < 10−7 M (c) > 10−7 M (d)  10−7 M

(ii) The pH of 10−8 M of HCl is _______.

(a) 8 (b) 7 (c) less than 7 (d) greater than 7

(iii) Which of the following solution will have pH value equal to 1.0?
(a) 50 mL of 0.1 M HCl + 50 mL of 0.1 M NaOH
(b) 60 mL of 0.1 M HCl + 40 mL of 0.1 M NaOH
(c) 20 mL of 0.1 M HCl + 80 mL of 0.1 M NaOH
(d) 75 mL of 0.2 M HCl + 25 mL of 0.2 M NaOH

(iv) Which of the following slats will give highest pH in water?

(a) KCl (b) NaCl (c) Na2CO3 (d) CuSO4

(v) Which of the following is an intensive property?

(a) Internal energy (b) Mass
(c) Temperature (d) Volume

(vi) Which of the following are NOT state functions?

1. Q+Q 2. Q 3. W 4. H − TS
(a) 1, 2 and 3 (b) 2 and 3 (c) 1 and 4 (d) 2, 3 and 4

(vii) 6.24 g of ethanol are vaporized by supplying 5.89 kJ of heat. Enthalpy of vaporization of ethanol
will be _____.
(a) 43.4 kJ mol−1 (b) 60.2 kJ mol−1
(c) 38.9 kJ mol −1
(d) 20.4 kJ mol−1

(viii) In which of the following, entropy of the system decreases?

(a) Crystallization of liquid into solid
(b) Temperature of crystalline solid is increased from 0 K to 115 K
(c) H2(g) ⎯→ 2H(g)
(d) 2NaHCO3(s) ⎯→ Na2CO3(s) + CO2(g) + H2O(g)

(ix) Consider the elements B, Al, Mg and K predict the correct order of metallic character :
(a) B > Al > Mg > K (b) Al > Mg > B > K
(c) Mg > Al > K > B (d) K> Mg> Al>B

(x) The lanthanides are placed in the periodic table at

(a) left hand side (b) right hand side
(c) middle (d) bottom
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 (xi) If the valence shell electronic configuration is ns2np5, the element will belong to
(a) alkali metals (b) halogens
(c) alkaline earth metals (d) actinides

(xii) Which of the atomic number represent the s-block elements?

(a) 7, 15 (b) 3, 12 (c) 6, 14 (d) 9, 17

(xiii) Which of the following pairs is NOT isoelectronic ?

(a) Na+ and Na (b) Mg2+ and Ne (c) Al3+ and B3+ (d) P3– and N3-

(xiv) Which molecule is linear?

(a) SO3 (b) CO2 (c) H2S (d) Cl2O

(xv) Valence Shell Electron Pair repulsion (VSEPR) theory is used to predict which of the following :
(a) energy levels in an atom (b) the shapes of molecules and ions.
(c) the electron negativities of elements. (d) the type of bonding in compounds.

(xvi) The angle between two covalent bonds is minimum in:

(a) CH4 (b) C2H2 (c) NH3 (d) H2O

Q. 2 ATTEMPT ANY FOUR [VSA] [2 marks Each]

(i) Define strong electrolytes.

(ii) Define pH and pOH.

(iii) What are acids and bases according to Lewis theory? Give an example.

(iv) Define acidic buffer solution.

(v) Explain : Closed system

(vi) Give four examples of extensive properties.

(vii) Write a short note on thermodynamic equilibrium.

(viii) What is enthalpy?

(ix) What was the basis of classification of elements before the knowledge of electronic structure of
atom?

(x) What is Mendeleev’s periodic law?

(xi) How many horizontal rows and vertical columns are present in the modern periodic table?
(xii) Name the scientists who made the classification of elements in the nineteenth century.

(xiii) Indicate the factor on which stalility of ionic compound is measured?

(xiv) The total number of electrons around sulphur (S) in SF6 is 12.
(xv) Give the type of overlap by which pi (π) bond is formed.

(xvi) Arrange the following compounds on the basis of lattice energies in decreasing (descending)
order: BeF2, AlCl3, LiCl, CaCl2, NaCl.

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 SECTION B

Q. 3 ATTEMPT ANY FIVE [SA] [2 marks Each]

(i) Derive the relationship between solubility and solubility product for a general salt BxAy.

(ii) What are the properties of buffer solutions?

(iii) Calculate the pH of 0.01 M sulphuric acid.

(iv) Under what conditions, H = U?

(v) Distinguish between isothermal process and adiabatic process

(vi) One mole of an ideal gas is compressed from 500 cm3 against a constant pressure of 1.2  105 Pa.
The work involved in the process is 36.0 J. Calculate the final volume.

(vii) Calculate the maximum work when 24 g of O2 are expanded isothermally and reversibly from the
pressure of 1.6 bar to 1 bar at 298 K.

(viii) Define :
a. Ionic radius
b. Electronegativity

(ix) With the help of diagram answer the questions given below:

a. Which atom should have smaller ionization enthalpy, oxygen or sulfur?

b. The lithium forms +1 ions while berylium forms +2 ions ?

(x) Select the smaller ion form each of the following pairs:
(a) K+, Li+
(b) N3-, F–

(xi) Why the second ionization enthalpy is greater than the first ionization enthalpy ?
(xii) Why the elements belonging to the same group do have similar chemical properties ?

(xiii) Distinguish between sigma and pi bond.

(xiv) Predict the shape and bond angles in the following molecules:
a. CF4
b. NF3
(xv) Define :
(a) Bond Enthalpy
(b) Bond Length

(xvi) Which type of hybridization is present in ammonia molecule? Write the geometry and bond angle
present in ammonia.

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 SECTION C
Q. 4 ATTEMPT ANY FOUR [SA- I] [3 Marks Each]

(i) Derive an expression for ionic product of water.

(ii) Dissociation constant of acetic acid is 1.8  10−5. Calculate percent dissociation of acetic acid
in 0.01 M solution.

(iii) What is the relationship between molar solubility and solubility product for the following
salts?
(i) AgBr (ii) PbI2 (iii) Al(OH)3

(iv) For the reaction,

CH4(g) + H2(g) ⎯→ C2H6(g),
Kp = 3.356  1017
Calculate G for the reaction at 25 C.

(v) Kp for the reaction, MgCO3(s) ⎯→ MgO(s) + CO2(g) is 9  10−10. Calculate G for the
reaction at 25 C.

(vi) The enthalpy change of the following reaction

CH4(g) + Cl2(g) ⎯→ CH3Cl(g) + HCl(g),
rH = − 104 kJ. Calculate C − Cl bond enthalpy. The bond enthalpies are

Bond C–H Cl – Cl H – Cl
H/kJ mol−1 414 243 431

(vii) Calculate the work done in the decomposition of 132 g of NH4NO3 at 100 C.
NH4NO3(s) ⎯→ N2O(g) + 2H2O(g)
State whether work is done on the system or by the system.

(viii) Write the outer electronic configuration of the following using orbital notation method.
Justify.
A. Ge (belongs to period 4 and group 14)
B. Po (belongs to period 6 and group 16)
C. Cu (belongs to period 4 and group 11)

(ix) La belongs to group 3 while Hg belongs to group 12 and both belong to period 6 of the
periodic table. Write down the general outer electronic configuration of the ten elements from
La to Hg together using orbital notation method.

(x) Explain the screening effect with a suitable example.

(xi) Give reasons for need of Hybridisation.

(xii) In Ammonia molecule the bond angle is 107°18 and in water molecule it is 104°35′, although
in both the central atoms are sp3 hybridized Explain.

(xiii) State octet rule. Explain its inadequecies with respect to

(a) Incomplete octet
(b) Expanded octet

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 SECTION D

Q. 5 ATTEMPTY ANY FOUR [LA] [4 Marks Each]

(i) If 20.0 cm3 of 0.050 M Ba(NO3)2 are mixed with 20.0 cm3 of 0.020 M NaF, BaF2 precipitate?
Ksp of BaF2 is 1.7  10−6 at 298 K.

(ii) One mole of liquid water is boiled at 100 C and 1 atm pressure. If the heat absorbed by water at 100
C is 40.670 kJ mol−1 then calculate the following values for the conversion of liquid water to water
vapour.
(i) Work done (W) (ii) Change in internal energy (U)
[Given: Density of liquid water = 1 g/mL]

(iii) How the atomic size vary in a group and across a period? Explain with suitable example.

(iv) Define ionization enthalpy. Name the factors on which ionisation enthalpy depends? How does it vary
down the group and across a period?

(v) Give reasons for need of Hybridisation.

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