CBSE Sample Papers for Class 12 Chemistry Paper 6 are part of CBSE Sample Papers for Class 12 Chemistry. Here we have given CBSE Sample Papers for Class 12 Chemistry Paper 6.
CBSE Sample Papers for Class 12 Chemistry Paper 6
Board | CBSE |
Class | XII |
Subject | Chemistry |
Sample Paper Set | Paper 6 |
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 6 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.
Write the formula of cyclotrimetaphosphoric acid.
Question 2.
Write the IUPAC name of:
Question 3.
Which will under go faster SN1 reaction:
Question 4.
Atoms of element Y forms ccp lattice and atoms of element X occupies 2/3rd of the tetrahedral voids. Find the formula of the compound.
Question 5.
A delta is formed at the meeting point of seawater and river water. Give reason for it.
Question 6.
Write the reagent required in the following reactions:
Question 7.
What will be your comment for the following solutions on variability from ideal behaviour.
- Solution of A (10 mL) mixed with B(10 mL) and the resultant solution is 18 mL.
- H2SO4 (cone.) and distilled water are at same temperature but on mixing temperature start rising.
Question 8.
- Write IUPAC name of the following complex:
K3[Co(C2O4)Cl2] - Write the formula for the complex potassium tetrachloridonickelate (II).
Question 9.
What will be the mass of Al deposited on the cathode when a current of 20 amperes is passed for 30 minutes in Al2(SO4)3 molten liquid.
Question 10.
Write one similarity and one difference between the chemistry of lanthanoids and that of actinoids.
Question 11.
Carry out the following conversions:
(a) Aniline to bromobenzene
(b) Chlorobenzene to 2-chloro acetophenone
(c) 2-Iodopropane to 2,3-dimethylbutane
Question 12.
- What type of stoichiometric defect is shown by KCl and why?
- Contrast conduction mechanism of n-type and p-type semiconductors.
- Give one example of a molecular solid.
Question 13.
Conductivity of 2.5 × 10-4 methanoic acid is 5.25 × 10-5 S cm-1. Calculate its molar conductivity and degree of dissociation.
(Given Δ0m for methanoic acid = 500 S cm2 mol-1 )
Question 14.
Complete the following reactions
Answer the following questions:
(a) Semicarbazide posses 2 NH2 group but only one reacts with carbonyl group which is attached with NH group. Why?
(b) Carboxylic acids are stronger acids than phenol. Why?
(c) Comment: HCHO can get oxidised as well as reduced in basic medium.
Question 15.
(a) Complete the following reaction
- KMnO4 + NO–2 \(\quad \underrightarrow { { H }^{ + } }\)
- FeCr2O4 + Na2CO3 +O2 \(\quad \underrightarrow { Heat } \)
OR
(b) Transition metals form complex compounds, give suitable reason.
Question 16.
Write the name and structure of the monomers of the following polymers:
(i) Polypropene
(ii) Terylene
(iii) Neoprene
Question 17.
50 mg of a solute dissolved in 100 ml of aqueous solution at 27°C shows an osmotic pressure of 20 kPa. Find the molar mass of this solute.
Question 18.
- Name the method used for refining of silicon to obtain it in highly pure state.
- What is the role of coke in extraction of iron?
- What is the role of froth stabliser in froth floatation process? Give example of one such stabliser.
Question 19.
Differentiate physisorption and chemisorption w.r.t
(a) Enthalpy of adsorption
(b) Reversibility
(c) Specificity
Question 20.
(a) Methoxy group present on benzene sing activities if for SE reaction at ortho and para position with respect to CH3 group. Explain.
(b) Complete the following reaction
(c) Explain Kolbe’s reaction with a suitable example.
Question 21.
- Name two secondary structures of protein.
- Name monosaccharides present in sucrose.
- Which vitamin B and vitamin B-complex part is fat soluble?
Question 22.
(a) Discuss hybridisation and magnetic behaviour of [Ni(CO)4] according to VBT.
(b) On the basis of CFT write the electronic configuration for d6 ion if Δ0 < P.
Question 23.
In our country people used to prepare pickle and even used to store some vegetables, fruits in dried form or in some cases as juice etc. All these need some or other form of preservative. On the basis of the above passage answer the following questions:
- What are food preservatives?
- What are antioxidants?
- What should be the additive for sweet pickles for diabetics?
- As a chemistry student what values are associated for your suggestion.
Question 24.
An aromatic compound ‘A’ of molecular formula C7H6O2 undergoes a series of reaction as shown below. Write the structure of A, B, C, D and E in the following reaction.
OR
(a) Write the structures of main products formed when benzene diazonium chloride reacts with the following:
(i) Phenol/OH–
(ii) C2H2OH
(iii) H3PO2 + H2O and heat
(b) Account for the following:
- Ethylamine is soluble in water, whereas aniline is not.
- Aniline does not undergo Friedel-crafts reaction.
Question 25.
Answer the following question on the basis of the given plot of potential energy is reaction co-ordinate:
- What is threshold energy for the reaction?
- What is the activation energy for forward reaction?
- What is the activation energy for backward reaction?
- What is the enthalpy change for the reaction?
- What is effect of catalyst on ΔG and Ea (Activation energy) of reaction?
OR
(a) The reaction between A and B is first order with respect to A and zero order with respect to B. Fill in the blanks in the following table.
Experiment | [A]/mol L-1 | [B]/mol L-1 | Initial rate (mol L-1 min-1) |
I | 0.1 | 0.1 | 2.0 x 10-2 |
II | — | 0.1 | 4.0 x 10-2 |
III | 0.4 | 0.4 | — |
IV | — | 0.2 | 2.0 x 10-2 |
(b) For a reaction
A + H2O → B, rate ∝ [A]
what is its
- molecularity
- order of reaction?
Question 26.
(a) Complete the following chemical equations:
- P4 + SO2Cl2 →
- Fe3+ + SO2 + H2O →
(b) Find basicity of H2S2O6.
(c)
- Bond angle in NH+4 is higher than NH3. Explain.
- Out of H2O and H2S, which one has higher bond angle and why?
OR
Account for the following
- H3PO4 is a stronger reducing agent than H3PO3.
- Stability of +5 oxidation state in group 1-15 elements decreases downwards.
- N2 is used to provide inert atmosphere in some chemical reactions.
- Clatharate compounds are not chemical compounds of noble gases in strict sense.
- Fluorine forms only one oxoacid HOF.
Answers
Answer 1.
(H3PO3)3
Answer 2.
2-Ethoxy-1-methoxy propane
Answer 3.
Answer 4.
X4Y3
Answer 5.
Silt present in river water gets coagulated due to mixing of salt from seawater during tidal waves leading to the formation of delta.
Answer 6.
(i) PCC (pyridinium chlorochromate)
(ii) NH3(aq)
Answer 7.
- Negative deviations from Ideal behaviour.
- There is a strong hydrogen bonding between H2O and H2SO4 molecules, so extra energy is released and temperature start rising.
Answer 8.
- Potassium dichloridodioxalato cobalt (III).
- K2[NiCl4]
Answer 9.
Since m = ZIt and Z = \(\frac { \mu }{ nF } \)
So m = \(\frac { \mu It }{ nF }\)
m = \(\frac { 27\times 20\times 30\times 60 }{ 3\times 96500 } \) = 3.358 g
Answer 10.
- Similarity: There is contraction in size of both lanthanoids and actinoids along the period.
- Difference: Lanthananoids exhibits a general oxidation state of +3 whereas actinoids show variable oxidation states.
Answer 11.
Answer 12.
- Schottky defect, due to comparable size of cation and anion.
- In n-type semiconductors, conduction is due to the movement of electrons and in p-type semiconductors it is due to the movement of holes in crystal lattice.
- Dry ice (solid CO2) is an example of a molecular solid.
Answer 13.
Δ0m = \(\frac { k }{ Molar\quad concentration }\) × 100
Answer 14.
(b) In the resonance structure of carboxylate ion, negative charge always resides on O atom, but in case of phenol negative charge shifts on the less electronegative carbon atom. Hence resonance contribution is negligible. Thus carboxylic acids are stronger acids than phenol.
(c) In basic medium HCHO get oxidised and reduced simultaneously.
HCHO \(\xrightarrow [ (conc.) ]{ NaOH } \) CH3OH + HCOONa
Answer 15.
(a)
- 2KMnO4 + 5NO2 \(\underrightarrow { { 6H }^{ + } }\) MnO2 + KNO3 + H2O
- FeCr2O4 + Na2CO3 + O2 \(\underrightarrow { Heat }\) Na2CrO4 + Fe2O3
(b) Due to variable oxidation state of transition metal, these form complexes.
Answer 16.
Answer 17.
Osmotic pressure(π):
Answer 18.
- Zone refining
- It acts as a fuel to provide heat and also acts as a reducing agent in the form of C and CO.
- Froth stabliser converts froth into thick scum and makes froth manageable, e.g. phenol, cresol etc.
Answer 19.
Parameters | Physisorption | Chemisorption |
(a) Enthalpy of adsorption (b) Reversibility (c) Specificity |
ΔHads = 20-40 kJ-lower Reversible Non-specific |
ΔHads = 80 – 240 kJ-much higher Irreversible Specific |
Answer 20.
(a) Due to resonance negative charge appears on the ortho and para positions, so the incoming electrophile will attack on these positions.
Answer 21.
- Two secondary structures of protein are:
- α-helix and
- β-pleated sheet structure
- α-D-Glucose and β-D-fructose
- Fat soluble part of vitamin B-complex-vitamin B12.
Answer 22.
Ni(CO)4 –
Ni in zero oxidation state
Ni → 3d8 4s2
Answer 23.
- Food preservatives: Chemical substances which are used to protect food against bacteria, yeast and moulds are called food preservatives, e.g. sodium metabisulphite, sodium benzoate etc.
- Antioxidants: These are the necessary food additives that helps in food preservation by retarding the action of oxygen on food. These are more reactive towards oxygen than foe food materials, e.g. butylated hydroxy toluene (BHT) and butylated hydroxyl anisole (BHA).
- Sucralose or Saccharin
- Concern for fellow countrymen, knowledge of chemistry, critical thinking.
Answer 24.
(b)
- There is hydrophobic aryl group in aniline, hence hydrogen bonding is less likely. In case of ethylamine hydrogen bonding is there with H2O, so it is more soluble.
- Aniline being a Lewis base combines with acid AlCl3, hence does not give Friedel Crafts reaction.
Answer 25.
(a)
- The minimum energy required by the reactants to get converted into product is known as threshold energy.
- -150 kJ/mol
- -200 kJ/mol
- ΔrH = -50 kJ/mol
- There will be no effect on free energy (ΔG) but Ea, i.e. activation energy usually decreases in the presence of catalyst.
OR
(a) rate = \(\frac { dx }{ dt }\) = k[A]1 [B]0
(b)
- Molecularity = 2
- Order = 1
Answer 26.
(a)
- P4 + 10SO2Cl2 → 4PCl5 + 10SO2
- Fe3+ + SO2 + H2O → Fe2+ + SO2-4
(c)
- There is no lone pair in NH+4 and hence tetrahedral angle will not be squeezed, as in case of NH3.
- H2O has higher bond angle than H2S, the reason being because there is less bond pair-bond pair repulsions in H2S. Hence ∠H-S-H angle is more compressed by lone pair-lone pair repulsions.
OR
- In H3PO3, P is in +3 oxidation state, so it can easily oxidised, secondly there is 1 P – H bond in H3PO3.
- It is due to inert pair effect.
- There is a strong triple bond present in N2, so it is used to provide inert atmosphere.
- Clathrate compounds: In such compounds noble gases gets trapped in voids of solid lattice of the solidified solvent and hence there is no chemical reaction. Hence clathrate compounds are not chemical compounds.
- Due to lack of d orbitals in fluorine.
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