CBSE Sample Papers for Class 12 Chemistry Paper 4 are part of CBSE Sample Papers for Class 12 Chemistry. Here we have given CBSE Sample Papers for Class 12 Chemistry Paper 4.
CBSE Sample Papers for Class 12 Chemistry Paper 4
Board | CBSE |
Class | XII |
Subject | Chemistry |
Sample Paper Set | Paper 4 |
Category | CBSE Sample Papers |
Students who are going to appear for CBSE Class 12 Examinations are advised to practice the CBSE sample papers given here which is designed as per the latest Syllabus and marking scheme as prescribed by the CBSE is given here. Paper 4 of Solved CBSE Sample Paper for Class 12 Chemistry is given below with free PDF download solutions.
Time Allowed : 3 Hours
Max. Marks: 70
General Instructions
- All questions are compulsory.
- Question number 1 to 5 are very short answer questions and carry 1 mark each.
- Question number 6 to 10 are short answer questions and carry 2 marks each.
- Question number 11 to 22 are also short answer questions and carry 3 marks each.
- Question number 23 is a value based question and carry 4 marks.
- Question number 24 to 26 are long answer questions and carry 5 marks each.
- Use log table, if necessary. Use of calculators is not allowed.
Questions
Question 1.
What is the reason for the stability of a colloidal sol?
Question 2.
Give an example of a molecular solid and a covalent solid.
Question 3.
Write structure of isomer of C4H9Br which is most likely give an elimination reaction.
Question 4.
Pb(NO3)2 on reaction with cone. H2SO4 gives a light brown gas which get intensified on adding copper turning. Identify the gas evolved on adding copper turning.
Question 5.
Write IUPAC name for
Question 6.
- Arrange the following according to increasing: KH value N2, NH3, CO2, H2.
- In non-ideal solution, what type of deviation shows the formation of maximum boiling azeotropes.
Question 7.
Write the structures of the following:
(i) XeF2
(ii) BrF–4
OR
What happens when
- H2S gas is passed in solution containing SO2 (aq)?
- XeF4 reacts with SbF5?
Question 8.
Write the chemical equation involved in the following reactions.
(i) Test involved Hinsberg reagent for 2° amine
(ii) Carbylamine reaction
Question 9.
When a coordination compound PtCl4.4NH3 is treated with excess of AgNO3 only 2 moles of AgCl are precipitated per mole of the compound. Thus, write the
(i) Structural formula of the complex
(ii) Geometrical isomer of complex, if possible.
Question 10.
For a reaction, H2 + Cl2 \(\underrightarrow { hv }\) 2HCl.
Rate = k
- Write the order and molecularity of this reaction.
- Write the unit of k.
Question 11.
An element X crystallises in fee lattice. 200 g of the element X contains 4.12 × 1024 atoms. The density of the element is 7.2 g/cm3. Calculate edge length of unit cell.
Question 12.
Calculate the freezing point of an aqueous solution when 3.58 g of K2SO4 was dissolved in 100 g of H2O, assuming complete dissociation of K2SO4. (Kf for H2O = 1.86 K kg mol-1)
Question 13.
Give reasons for the following:
- NCl5 is not known.
- SO2 is reducing while TeO2 is an oxidising agent.
- Halogens are coloured.
Question 14.
Write the final products in each of the following reaction
Question 15.
Explain the following terms:
- Critical micelle concentration (CMC)
- Freundlich adsorption isotherm’s formula
- Alcohophilic sol
Question 16.
- Name the method used for refining of titanium.
- Name the method for concentration of ore in which Bayer’s process is used.
- What is the role of limestone in the extraction of iron from its oxide?
Question 17.
For the first order thermal decomposition reaction the following data were obtained:
Calculate the rate constant.
(Given log 2 = 0.3010, log 3 = 0.477 or log 4 = 0.602)
Question 18.
Give reason for the following:
- Aniline does not undergo Friedel crafts reaction.
- (CH3)3N is less basic than (CH3)2NH in aqueous solution, though inductive effect of 3 methyl groups is more.
- Tertiary amines have minimum boiling point as compared to other isomeric amines.
Question 19.
How do you convert:
(i) Bromobenzene to benzene
(ii) Propene to 1-iodopropane
(iii) 2-Butene to 2-Butyne
OR
Write the major products in the following:
(ii) Br-CH2-CH2-CH2-CH2-Br \(\xrightarrow [ dryether ]{ Na } \) ?
(iii) CH3CH2Br \(\underrightarrow { AgCN } \) ?
Question 20.
(i) What properties of rubber are improved on vulcanisation?
(ii) Write monomers of glyptal.
(iii) Arrange following polymers in increasing order of intermolecular forces.
Terylene, Polyethene, Neoprene
Question 21.
- Write the structural difference between amylose and amylopectin.
- What type of linkage is present between nucleotides?
- Write differences (any two) between DNA and RNA.
Question 22.
In the following complexes:
[Fe(H2O)6]2+, [Co(CN)6]3-, [Ni(NH3)6]2+, which complex will be
- Diamagnetric and inner -d complex
- Paramagnetic and high spin complex
- Octahedral and outer-d-complex.
Question 23.
Harish was feeling headache. His friend Vikram observed that Harish had fever. He advised him to take two tablets of ofloxacin – 200 mg.
- In your opinion, is it right to take medicine as per Vikram’s advice.
- Give reason for your answer.
- If you were a doctor, which class of medicine would have you suggested.
- Write values associated with his friends decision.
Question 24.
(i) Calculate E0cell for the following cell:
Al(s) /Al3+(aq) (0.01 M) || Cu2+(aq) (0.01 M) | Cu(s)
Given that Ecell = 1.98 V
(ii) Using the E° values of A and B predict which is better for coating the surface of iron [E°(Fe2+/Fe) = -0.44V] to prevent corrosion and why?
Given E°(A2+/A) = -2.37 V, E° (B2+/B) = -0.14V
OR
Consider the figure given below and answer the questions (i) to (v)
- Write the direction of electron flow.
- Is silver plate acting as an anode or a cathode?
- What will happen if salt bridge is removed?
- When will the cell stop functioning?
- How will concentration of Zn2+ ions and Ag+ ions be affected when the cell functions?
Question 25.
(a) Explain following observations:
- Transition metals show maximum oxidation state in oxides rather than fluorides.
- d1 configuration for transition metal ions is quite unstable.
- TiCl4 is colourless.
(b) Complete the following reactions:
- K2MnO4 \(\underrightarrow { { Cl }_{ 2 }(aq) }\)
- Na2CrO4 \(\underrightarrow { { dilH }_{ 2 }{ SO }_{ 4 } } \)
OR
For the elements Z = 11 (Sc) to Z = 30 (Zn), answer for the following questions:
- Write the element which shows maximum number of oxidation states.
- Name the element with maximum m.pt.
- Which element show only +3 oxidation state?
- The element with strong oxidising action in +3 state.
- The element which readily changes from in +1 state to +2 state in aqueous solution.
Question 26.
Complete the following reaction sequence and write structure and A, B, C, D and E.
OR
(a) Arrange the following as per given instruction:
(i) CH3CHO, CH3COOH, CH3CH2OH (increasing B.Pt)
(b) Why carboxylic acid does not give test for carbonyl group?
(c) Write chemical reaction involved in the following named reactions:
(i) Wolff-Kishner reduction
(ii) Cross aldol condensation
Answers
Answer 1.
Charge on particles of dispersed phase repels one another and brownian movement stabilises colloidal sol and prevents such sol to settle under gravity.
Answer 2.
Molecular solid – Solid CO2, ice
Covalent solid – SiO2, SiC, Diamond etc.
Answer 3.
Answer 4.
NO2 gas
Answer 5.
4-Hydroxybenzoic acid
Answer 6.
- NH3 < CO2 < N2 < H2
- Negative deviation from ideal solution causes formation of maximum boiling azeotropes.
Answer 7.
OR
- Sulphur sol will form
H2S(g) + SO2(aq) → Sx + H2O - XeF4 + SbF5 → [XeF3]+ [SbF6]–
Answer 8.
This reaction is known as carbylamine reaction, used for the test of primary amines.
Answer 9.
(i) [Pt(NH3)4Cl2]Cl2
Answer 10.
- Order of reaction – Zero order
Molecularity of reaction – 2 - Units of k – mol L-1 s-1
Answer 11.
It is given that
fee arrangement i.e. Z = 4
mass of sample (m) = 200 g,
no. of atoms in sample = 4.12 × 1024,
density of solid = 7.2 g/cm3,
edge length (a) = ?
d = \(\frac { Zm }{ { a }^{ 3 }n } \)
where m = mass of sample and n = no. of particles in sample.
Answer 12.
ΔTf = 1.148 ≈ 1.15 K
ΔTf = T0f – Tf = 1.15
Tf = 273.15 – 1.15 = 272 K
Answer 13.
- Due to lack of d orbitals in nitrogen it cannot expand its covalency beyond 4.
- In group XVI the stability of (+ VI) oxidation state decreases down the group, hence TeO2 is oxidising but SO2 is reducing and easily get oxidised to (+ VI) state.
- Halogens absorb light in visible region and electrons of antibonding molecular orbitals \({ \pi }_{ { np }_{ x } }^{ \ast }\) = \({ \pi }_{ { np }_{ y } }^{ \ast }\) get easily excited in the corresponding \({ \sigma }_{ { np }_{ z } }^{ \ast }\) antibonding orbital, hence halogens are coloured.
Answer 14.
Answer 15.
- The concentration of electrolyte (soap like) when increases just above a particular concentration where associated colloid (micelle) formation takes place is known as critical micelle concentration (CMC).
- Freundlich adsorption isotherm formula:
\(\frac { x }{ m }\) = kP1/n where \(\frac { x }{ m }\) = mass of adsorbate per unit mass of adsorbent
k = constant of adsorption
n = number of layers of adsorption. - Alcohophilic sol: The lyophilic sol (Solvent loving) in which alcohol is taken as solvent is known as “alcohophilic sol.”
Answer 16.
- Van Arkel method
- Aluminium
- Limestone, CaCO3 provides CaO and CO2 respectively used as flux and forms CO on reaction with carbon.
- CaO + SiO2 → CaSiO3
- C + CO2 → 2CO (Acts as reducing agent)
Answer 17.
Answer 18.
- Aniline forms adduct with AlCl3. It is an acid base reaction and forms salt, hence Friedel Crafts reaction is not possible.
- The hydrolysis (solution) of secondary amine is much more which can overshadow slightly more inductive effect of three methyl groups, hence secondary amine is more basic in aqueous solution as compared to tertiary amine.
- It is because primary and secondary amines are associated with intermolecular hydrogen bonding whereas tertiary amines are not.
Answer 19.
Answer 20.
(i) On valcalisation rubber becomes less sticky, solvent and heat resistant as well as thermal stability and elastic property increases.
(iii) Neoprene < Polyethene < Terylene
Answer 21.
- Amylose is a straight chain polymer of α-D-glucose whereas amylopectin is a highly branched chain polymer of α-D-glucose.
- Phosphodiester linkage is present between nucleotides.
- Difference between DNA and RNA
DNA |
RNA |
It consists of pentose sugar de-oxy ribose. |
It consists of pentose sugar ribose. |
It consists of pyrimidine base thymine. |
It consists of pyrimidine base uracil. |
It carries genetic materials. |
It is responsible for protein synthesis. |
Answer 22.
- [CO(CN)6]3-
- [Fe(H2O)6]2+
- [Ni(NH3)6]2+
Answer 23.
- No, reason being Vikram is not expert for suggesting medicine.
- Ofloxacin-200 mg is an antibiotic, so it is not for the purpose of headache and fever.
- Analgesic
- Concern for friend but lacking knowledge of medicine.
Answer 24.
(ii) For protecting iron surface the reduction potential of the protecting metal should be more negative than iron, i.e. A will be better to protect iron metal. A will get oxidised in preference to iron and thus, iron will be protected.
OR
- Electron will flow from zinc plate to silver plate.
- Silver plate will act as cathode.
- The circuit will disrupt and no reaction will take place on either electrode.
- When either Zn electrode or Ag+ ion will exhaust.
- Zn2+ ion concentration will increase and Ag+ ion will decrease.
Answer 25.
(a)
- In oxides, there is dπ-pπ multiple bonding between M and ‘O’ and have high lattice energy as compared to fluorides, hence maximum oxidation state is achieved in oxides.
- The ions with d1 configuration have the tendency to lose electron to acquire noble gas configuration. Therefore, they are unstable and undergoes oxidation or disproportionation.
- In TiCl4, Ti exist as Ti4+ ion and hence have d° configuration as a result TiCl4 is colourless.
(b)
- 2 K2MnO4 \(\underrightarrow { { Cl }_{ 2 }(aq) }\) 2KMnO4 +2KCl
- 2Na2CrO4 \(\underrightarrow { { dilH }_{ 2 }{ SO }_{ 4 } } \) Na2Cr2O7 + Na2SO4 + H2O
OR
- Mn (Manganese)
- Chromium (Cr)
- Scandium (Sc)
- Mn3+ (Manganese)
- Copper (Cu+)
Answer 26.
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