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Call and WhatsAppNIOS April 2025 Sr. Secondary Chemistry (313) Solved Paper
SECTION: A
MCQ Questions
Question number 1 to 16 are multiple choice questions of 1 mark each.
1. Tertiary amines have:
a) One lone pair of electrons on nitrogen
b) Two lone pairs of electrons
c) No lone pair on nitrogen
d) Three hydrogen atoms on nitrogen
View Answer
One lone pair of electrons on nitrogen.
2. Which of the following is most acidic?
a) Butanoic acid
b) 2-chlorobutanoic acid
c) 3-chlorobutanoic acid
d) 4-chlorobutanoic acid
View Answer
2-chlorobutanoic acid.
3. The hybridization of oxygen in ethers is:
a) sp
b) sp2
c) sp3
d) dsp2
View Answer
sp3
4. Butan-1-ol on reaction with PCC gives:
a) Butanone
b) Propanal
c) Butanal
d) Butanoic acid
View Answer
Butanal.
5. The organometallic compounds obtained by the reaction of magnesium metal with alkyl or aryl halides are called:
a) Grignard reagents
b) Bayer’s reagents
c) Fehling’s solution
d) Hinsberg’s reagent
View Answer
Grignard reagents.
6. Alkenes and alkynes can be distinguished by:
a) Br2/CCl4
b) Alkaline KMnO4
c) Ammoniacal AgNO3
d) H2/Pd
View Answer
Alkaline KMnO4.
7. Enantiomers are:
a) Superimposable mirror images of a compound
b) Non-superimposable mirror images of a compound
c) Superimposable compounds
d) Non-superimposable compounds
View Answer
Non-superimposable mirror images of a compound.
8. The empirical formula of S3O9 is:
a) SO2
b) SO3
c) S2O4
d) S4O12
View Answer
SO3.
9. Which of the following is not necessary for the molar volume of a gas?
a) 0°C
b) 1 bar
c) 1 mole
d) 278 K
View Answer
278 K.
10. The number of moles present in 73.0 g of HCl is:
a) 1
b) 2
c) 3
d) 4
View Answer
2.
11. Law of definite proportions states that:
a) A given compound always contains exactly the same proportion of elements by mass
b) The same elements can combine in different ratios to form different compounds
c) The composition can vary
d) Atoms can be variable
View Answer
A given compound always contains exactly the same proportion of elements by mass.
12. The mass number of an atom is the sum of:
a) Electrons and protons
b) Electrons and neutrons
c) Neutrons and protons
d) Protons only
View Answer
Neutrons and protons.
13. The formation of ionic compound is favored by:
a) High ionization energy of metal
b) Low ionization energy of metal
c) Low electron affinity of non-metal
d) Low lattice energy
View Answer
Low ionization energy of metal.
14. The isotope of hydrogen with two neutrons is:
a) Protium
b) Deuterium
c) Tritium
d) Both B and C
View Answer
Tritium.
15. The correct order of acid strength of oxoacids of chlorine is:
a) HOClO3 > HOClO2 > HOClO > HOCl
b) HOCl > HOClO2 > HOClO > HOClO3
c) HOCl > HOClO > HOClO2 > HOClO3
d) HOClO3 > HOClO > HOClO2 > HOCl
View Answer
HOClO3 > HOClO2 > HOClO > HOCl.
16. Two elements with almost identical atomic radii due to lanthanoid contraction are:
a) La and Lu
b) Ce and Lu
c) Zr and Hf
d) Ce and Hf
View Answer
Zr and Hf.
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Question number 17 to 28 are objective type questions of 2 mark each.
17. Write True (T) for correct statement and False (F) for incorrect statement:
(1) In Buna-S, Bu stands for butadiene, Na for sodium and S for styrene.
Answer: True (T)
(2) Chloroprene is a polymer obtained from neoprene.
Answer: False (F)
18. Read the passage given below and answer the following questions.
Detergents are widely used as cleaning agents. When dissolved in water, its molecules tend to concentrate at the surface of the solution or at interface. Their hydrophilic group makes them soluble in water. Depends on the nature of hydrophilic part synthetic detergents are anionic, cationic or non-ionic type.
(1) Name the anion present in detergents.
Answer: Sulphate ion (SO₄²⁻) or sulphonate ion depending on detergent type
(2) How many carbon atoms in sodium lauryl sulphate carbon chain?
Answer: 12 carbon atoms
19. Write True (T) for correct statement and False (F) for incorrect statement:
(1) Hybrid orbitals of a molecule are all unequivalent orbitals and have different energies.
Answer: False (F)
(2) On the basis of VSEPR, methane molecule is tetrahedral.
Answer: True (T)
20. Read the passage given below and answer the following questions.
Alcohols have hydroxyl group as a functional group. When the hydroxyl group is attached to primary, secondary and tertiary carbon atom, the alcohols are known as primary, secondary and tertiary alcohols. They hardly exhibit any acidic character. They are generally toxic in nature. On dehydration they either produce alkenes or ethers.
(1) Name a test to distinguish primary, secondary, and tertiary alcohols.
Answer: Lucas test
(2) Conditions to produce ether from ethanol?
Answer: Concentrated sulfuric acid, 140°C temperature
21. Match Column I with Column II:
(a) [PtCl6]2- → (2) oxidation state 4
(b) [Ag(NH3)2]+ → (1) oxidation state 1
(c) [Fe(CN)6]4- → (3) oxidation state 2
(d) [Cr(H2O)4Cl2]+ → (4) oxidation state 3
22. Complete the following by given options below
2, 3, diamagnetic, paramagnetic, ferromagnetic
(1) Bond order of nitrogen molecule is 3
(2) Molecules with all paired electrons are diamagnetic.
23. Complete the following by given options below
acidic, basic, amphoteric, carnalite, chile salt peter
(1) Hydroxide of aluminium is amphoteric
(2) Common ore of magnesium is carnallite
24. Read the passage given below and answer the following questions.
Sulphuric acid is known as the king of chemicals. It is used in the manufacture of fertilizers, paints and pigments, detergents etc. Dilute sulphuric acid is obtained from concentrated sulphuric acid. Improper method of dilution throws out drops of sulphuric acid and may cause burns.
(1) Which property of sulphuric acid converts carbohydrates into black carbon mass?
Answer: Dehydrating property
(2) How is concentrated sulphuric acid diluted?
Answer: By slowly adding acid to water with stirring.
25. Complete reactions:
(1) CH2=CH2 + H2O → CH3CH2OH (with H2SO4 and heat)
(2) CH3CHBr2 + alc. KOH → CH2=CHBr + KBr + H2O (elimination reaction).
26. Read the passage given below and answer the following questions.
The elements from groups 3 to 12 occupy the middle portion of the periodic table. The last electron is filled in the penultimate d-subshell. These elements are metallic in nature. The d-block elements represent a change from the most electropositive s-block to the least electropositive p-block and hence are called transition elements.
The following questions are multiple choice questions.
Choose the most apropriate answer
Identify the correct statement among the following
(a) Zn, Cd, and Hg are not considered transition elements
(b) d orbitals can hold a maximum of 5 electrons
(c) Transition elements shows low melting amd boiling points.
(d) Densities of transition elements are low as compared to than those of s-block elements
Answer: (a) Zn, Cd, and Hg are not considered transition elements because their d-orbitals are completely filled in the ground as well as common oxidation states.
(2) Why is copper regarded as a transition element despite its 3d¹⁰4s¹ configuration?
Answer: Because copper can have an incomplete d-orbital in its excited state and forms cations with incomplete d-subshells, qualifying it as a transition element.
27. Complete the following by given options below
distance, mass, velocity, weak, strong
(1) The principal quantum number determines the ----- of the electron from the nucleus.
Answer: distance
(2) The electrostatic force of attraction between the ions in an ionic compound is -----.
Answer: strong
28. Read the passage given below and answer the following questions.
Water is an inorganic, miracle compound. It exist in three forms- solid, liquid and vapour. In winters, lakes freeze and forms ice on the surface on water.
(1) "H2O and HF, though covalent compounds, have high boiling points." Justify.
Answer: Due to strong hydrogen bonding between molecules.
(2) Why is solid water (ice) less dense than liquid water?
Answer: Because ice has an open hexagonal structure formed by hydrogen bonding, making it less dense than liquid water.
SECTION: B
Question number 29 to 43 are subjective type questions. An internal choice has been provided in some of these questions.
29. A sample of lime juice has a hydronium ion concentration of 7.3×10−2 M. Calculate its pH.
[log 7.3 = 0.8633, log 10 = 1].
OR
Calculate the pH of a solution containing 0.05 M benzoic acid and 0.025 M sodium benzoate. Benzoic acid has a pH of 4.2.
[log 2 = 0.3010]
30. Define a closed system. Give an example.
31. Define enthalpy of formation. The enthalpy of formation of CO2(g) is 393.5 kJ mol−1. Represent this in the form of a chemical equation.
OR
The bond dissociation energies for the first and second steps of H2O dissociation are 502 kJ mol−1 and 427 kJ mol−1 respectively. Represent them in chemical equations.
32. Draw a graph for a liquid pair A and B, depicting negative deviation from Raoult’s law.
OR
Define Van’t Hoff factor. What will be its value when the solute undergoes dissociation in solution?
33. Define Bronsted-Lowry concept of acids and bases. Identify Bronsted-Lowry acid and base in the reaction:
NH3 + HF → NH4+ + F−
34. What is a buffer solution? Give one example each of acidic and basic buffer.
35. What is the essence of Hess’s law of constant heat summation? What is a useful application of this law?
OR
Are ∆Hsub∘ and ∆Hfusion∘ the same or different? Justify.
36. Why do transition metals show catalytic properties? Explain.
37. What happens when benzene reacts with chlorine in the presence of iron as a catalyst? Give the chemical equation and name the type of reaction.
38. The vapour pressure of water is 12.3 kPa at 300 K. Calculate the vapour pressure of 1 molal solution of a solute in it.
39. Define electron gain enthalpy. Which atom among F and Cl has a greater electron gain enthalpy? Give reason.
OR
Mention two reasons responsible for the “inert pair effect”. What is the consequence of this effect on the oxidation states of Tl and Pb?
40. Describe the composition of a lead storage battery. Write chemical equations for the reactions taking place in it.
41. Define normal boiling point of a solution. Draw a graph depicting elevation in boiling point.
OR
(a) What is meant by mole fraction? For a solution with components A and B, write the formula for mole fraction of component B.
(b) Define molality.
42.
(a) How is potassium permanganate manufactured from the ore pyrolusite? Give chemical equations.
(b) Give IUPAC names for complexes:
(i) [Pt(NH3)2Cl2]
(ii) [Co(en)2Cl2]Cl
OR
(a) Draw the structures of XeF2 and XeOF4. Mention hybridization and shape.
(b) How does sulphuric acid oxidise metals and non-metals? Illustrate with examples.
43.
(a) Which compounds show optical isomerism?
(b) Draw optical isomers of 1,2-dihydroxy propane.
(c) Write chemical equations for:
(i) Wurtz reaction
(ii) Sandmeyer reaction
OR
(a) How is phenol prepared by Dow process?
(b) Write chemical equations for:
(i) Reimer-Tiemann reaction
(ii) Coupling reaction
(c) Arrange in increasing order of acidity: 2-Chlorophenol, 2-Methylphenol, phenol.