Plus Two Chemistry Model Question Paper 5

Time: 2 Hours
Cool off time: 15 Minutes
Maximum: 60 Scores

General Instructions to candidates

  • In addition to the two hours of writing time, there is a 15-minute ‘cool off time’.
  • Use the ‘cool off time’ to familiarize yourself with the questions and to prepare your answers.
  • Read questions carefully before you answering.
  • Make sure you read the instructions carefully.
  • Calculations, figures, and graphs should be shown in the answer sheet itself.
  • The questions are available in Malayalam as well.
  • Give equations wherever necessary.
  • Except for nonprogrammable calculators, electronic devices are not allowed in the Examination Hall.

Plus Two Chemistry Model Question Papers Paper 1 33

Questions from 1 to 7 carry 1 score. Answer any 6 questions.
Plus Two Chemistry Model Question Papers Paper 5 imp1

Question 1:
The edge length and axial angles of a unit cell are a = b = c and α = β = γ = 90° respectively. Identify the type of Crystal System.
Plus Two Chemistry Model Question Papers Paper 5 Q1

Question 2:
Name the polymer used for non-stick surface coated utensils
Plus Two Chemistry Model Question Papers Paper 5 Q2

Question 3:
Which of the following forms colored compounds.
Plus Two Chemistry Model Question Papers Paper 5 Q3
i. Sc3+
ii. Cr2+
iii. Zn3+
iv. Cu+
[Atomic number Sc – 21, Cr – 24, Zn – 30, Cu – 29]

Question 4:
The rate expression of a reaction is Rate = K [A]12 [B]12. Calculate its overall order.
Plus Two Chemistry Model Question Papers Paper 5 Q4

Question 5:
Among the following amines, identify the one that does not reach with Hinsberg reagent
Plus Two Chemistry Model Question Papers Paper 5 Q5
i. C2H5NH2
ii. (CH3)2NH
iii. (C2H5)2NH
iv. (CH3)3N

Question 6:
The Carbohydrate, that is known as ‘animals starch’ is ………
Plus Two Chemistry Model Question Papers Paper 5 Q6

Question 7:
Name the class of drug used for the treatment of stress and mental diseases.
Plus Two Chemistry Model Question Papers Paper 5 Q7

Questions from 8 to 20 carry 2 score. Answer any 10 questions.
Plus Two Chemistry Model Question Papers Paper 5 imp2

Question 8:
Write the names and structure of the monomers of the polymer Buna – S
Plus Two Chemistry Model Question Papers Paper 5 Q8

Question 9:
Calculate the packing efficiency in body centred cubic structure.
[Given that r = 3√2a, Where ‘r’ is the radius of sphere and ‘a’ is the edge length of unit cell]
Plus Two Chemistry Model Question Papers Paper 5 Q9
Plus Two Chemistry Model Question Papers Paper 5 Q9a

Question 10:
Write one method for the preparation of sulphur dioxide. How is its presence detected?
Plus Two Chemistry Model Question Papers Paper 5 Q10

Question 11:
Write the IUPAC names of following com-pounds.
Plus Two Chemistry Model Question Papers Paper 5 Q11
(a) K3[Fe(CN)6]
(b) CO[Cl2(en)2Cl

Question 12:
Define Van’t Hoff factor ‘i’. What would be the value of ‘i’ for a dilute solution of K2SO4 in water?
Plus Two Chemistry Model Question Papers Paper 5 Q12

Question 13:
By taking ethyl bromide as starting material, prepare ethyl iodide and ethyl fluoride.
Plus Two Chemistry Model Question Papers Paper 5 Q13

Question 14:
Write the complete reaction representing the disproportionation of benzaldehyde.
Plus Two Chemistry Model Question Papers Paper 5 Q14

Question 15:
Vapour pressure of water at 293 K is 17.535 mm Hg. Calculate the vapour pressure of water at 293 K when 25 g of glucose is dissolved in 450 g of water.
Plus Two Chemistry Model Question Papers Paper 5 Q15

Question 16:
Name the products of hydrolysis of sucrose is not a reducing sugar.
Plus Two Chemistry Model Question Papers Paper 5 Q16

Question 17:
Tetiary buty bromide react with aqueous NaOH to give tertiary butyl alcohol proceeds via SN1 reaction. Write the mechanism of the reaction.
Plus Two Chemistry Model Question Papers Paper 5 Q17

Question 18:
Give the structures of A and B in the following reaction.
Plus Two Chemistry Model Question Papers Paper 5 Q18

Question 19:
Match the following
Plus Two Chemistry Model Question Papers Paper 5 Q19

Question 20:
Write a simple chemical test to distinguish ethanal from propanone.
Plus Two Chemistry Model Question Papers Paper 5 Q20

Questions from 21 to 29 carry 3 score. Answer any 6 questions.
Plus Two Chemistry Model Question Papers Paper 5 imp3

Question 21:
The resistance of a 0.5 M solution of an electrolyte enclosed between two platinum electrode 1.5 cm apart and having an area of 2.0 cm2 was found to be 30Ω. Calculate the molar conductivity of the solution.
Plus Two Chemistry Model Question Papers Paper 5 Q21

Question 22:
write notes on different allotropic forms of phosphorous.
Plus Two Chemistry Model Question Papers Paper 5 Q22

Question 23:
Integrated rate equation for a first order reaction.
Plus Two Chemistry Model Question Papers Paper 5 Q23
a. Derive an expression for half life of first order reaction
Plus Two Chemistry Model Question Papers Paper 5 Q23A
b. Find the half life of first order reaction having rate constant K = 5.5 x 10-14S-1
Plus Two Chemistry Model Question Papers Paper 5 Q23B

Question 24:
What are adsorption isotherms? Write the Freundlich absorption isotherm equation and plot agraph based on it.
Plus Two Chemistry Model Question Papers Paper 5 Q24

Question 25:
Describes the steps involved in the manufacture of sulphuric acid by contact process.
Plus Two Chemistry Model Question Papers Paper 5 Q25

Question 26:
Differentiate ferrimagnetism from paramagnetism and predicts the change that takes place to ferrimagnetic substances on heating.
Plus Two Chemistry Model Question Papers Paper 5 Q26

Question 27:
a. Draw the structure of dichromate ion.
b. How can dichromate ion be converted to chromate ion?
c. Write examples for the oxidising action of potassium dichromate in acidic medium.
Plus Two Chemistry Model Question Papers Paper 5 Q27

Question 28:
Explain the following
a. Hydraulic washings
b. zone refining
c. Roasting of ores
Plus Two Chemistry Model Question Papers Paper 5 Q28
Plus Two Chemistry Model Question Papers Paper 5 Q28A

Question 29:
Describe the following reactions.
a. Aldol condensation
b. Etard reaction
c. Rosenmund reduction
Plus Two Chemistry Model Question Papers Paper 5 Q29

Questions from 30 to 33 carry 4 score. Answer any 3 questions.
Plus Two Chemistry Model Question Papers Paper 5 imp4

Question 30:
Write chemical equations for the conversion of phenol to acetyl salicylic acid (aspirin)
Plus Two Chemistry Model Question Papers Paper 5 Q30

Question 31:
With the help of diagram describe the construction and working of a fuel cell using H2, and O2. What are the advantages of fuel cell over conventional cells.
Plus Two Chemistry Model Question Papers Paper 5 Q31
Plus Two Chemistry Model Question Papers Paper 5 Q31a

Question 32:
Sketch the Crystal field splittng of d-orbit- als of the Central metal ion in [CoF6]3-. Also write the electronic configuration of central metal ion and predict its magnetic behaviour based on crystal field theory.
Plus Two Chemistry Model Question Papers Paper 5 Q32

Question 33:
Give the structure and IUPAC names of the products formed on the following reactions
a. Hydration of propene in the presence of dilute sulphuric acid.
b. Reaction of methanal with methyl mag-nesium bromide followed by hydrolysis.
Plus Two Chemistry Model Question Papers Paper 5 Q33

Answers

Answer 1:
Cubic

Answer 2:
Teflon

Answer 3:
Cr2+(4 unpaired d electrons)

Answer 4:
Order of the reaction = 12 + 32 = 42 = 2

Answer 5:
iv

Answer 6:
Glycogen

Answer 7:
Tranquilizers

Answer 8:
Plus Two Chemistry Model Question Papers Paper 5 A8

Answer 9:
In bcc
Plus Two Chemistry Model Question Papers Paper 5 A9

Answer 10:
Sulphur dioxide is formed together with a little (6 – 8%) sulphur trioxide when sul¬phur is burnt in air or oxygen.

S(s) + O2(g) → SO2(g)

SO2 is a colourless and pungent smell gas It can detected by using potassium permag- nate solution when SO2 is passed through an acidified potassium permanganate solu¬tion, then it decolonises the solution as it reduces MnO4 ions to Mn2+ ions. SO2 give out suffocating smell which indicates its presence

Answer 11:
a. Potassium hexacyanoferrate (III).
b. Dichloridobis (ethane -1,2- diamine) cobalt (III) chloride.

Answer 12:
Vant Hoff factor is the ratio of the observed college five property to the normal colligative property
i = observedcollegativepropertyTheoreticalcollegativeproperty
Dilute solution of K2SO4( would dissociate into two K+ ions and a sulphate ion.
K2SO4 → 2K+ + SO42-
The Van’t hoff factor for a dilute solution of K2SO4 is 3.

Answer 13:
Plus Two Chemistry Model Question Papers Paper 5 A13

Answer 14:
Cannizzaro reaction which do not have an a-hydrogen atom, undergo self oxidation and reduction (disproportionation) reaction on heating with concetrated alkali. In this reaction, one molecule of the aldehyde is reduced to alcohol while another is oxidised to carboxylic acid salt.
Plus Two Chemistry Model Question Papers Paper 5 A14

Answer 15:
Plus Two Chemistry Model Question Papers Paper 5 A15

Answer 16:
Hydrolysis of sucrose gives equimolar mixture of D – (+) – glucose and D – (-) fractose.
Plus Two Chemistry Model Question Papers Paper 5 A16
Sucrose ¡s non-reducing sugar because aldehyde group of glucose and keto group of fractose are not fuce and involved in glycosidic bond formation.

Answer 17:
The reaction between tert-butyl bromide and hydroxide ion yields tert-butyl alcohol and follows the first of order kinetics, i.e, the rate of reaction depends upon the concetration of only one reactant, which is tert butyl bromide.
(CH3)3 CBr + NaOH → (CH3)3COH + NaBr
If occurs in two steps
Step I : The polarised C-Br bond under¬goes slow clearage to produce a carbocation and a bromide ion. The carbocation thus formed is then attacked by nucleophile in step II to complete the substitution reaction.
Plus Two Chemistry Model Question Papers Paper 5 A17

Answer 18:
Plus Two Chemistry Model Question Papers Paper 5 A18

Answer 19:
a. Antiseptic                                  –            bithional
b. Artificial sweetners                 –            Saccharin
c. Soap                                            –            Sodium stearate
d. Vitamin C                                  –           ascorbic acid

Answer 20:
Ethanal give silver mirror with tollens reagent where as propanone will not react

Answer 21:
Plus Two Chemistry Model Question Papers Paper 5 A21
Plus Two Chemistry Model Question Papers Paper 5 A21A

Answer 22:
There are 3 allotropic forms of phosphorus.

White phosphrous:

  • Translucent white waxy solid
  •  Garlic smell
  • Poisonous
  •  Less stable due to angle strain. (60° PPP bond angle)
  • Readily catches fire in air.
    Plus Two Chemistry Model Question Papers Paper 5 A22

Red phosphorus:

  • Iron grey lustrous powder
  • Odourless
  • Non-poisonous
  •  More stable than white phosphorus
    Plus Two Chemistry Model Question Papers Paper 5 A22A

Black phosphorus:
It has two forms α black phosphorus and β black phosphorus. When white phosphorus is heated under high pressure at 473 K β black phosphorus is formed.

Answer 23:
Plus Two Chemistry Model Question Papers Paper 5 A23
Plus Two Chemistry Model Question Papers Paper 5 A23A

Answer 24:
The relationship between extent of adsorption and pressure of the gas at constant temperature is called adsorption isotherm and is given by
xm = kp 1n (n> 1)
Freundlich Adsorption Isotherm
where x = mass of gas adsorbed on ‘m’ mass of the adsorbent at p pressure, k, n are constants.

Observations:

  • At low pressure xm ∝ p (graph is linear).
  •  At high pressure xm is independent of p (graph – straight line).
  • At intermediate pressure xm = kp1n

Plus Two Chemistry Model Question Papers Paper 5 A24
Taking logarithm on both sides. We get
Plus Two Chemistry Model Question Papers Paper 5 A24a
In case of a solution, the isotherm takes the form, x = k(C)1n

Answer 25:
H2SO4 is manufactural by the contact process which involves three steps
(1) Burning of sulphur or sulphide uses in air to generate SO2
S + O2 → SO2

(2) Conversion of SO2 to SO3 by the reaction with oxygen in the presence of a catalyst
2SO2(g) + O2(g) V2O5−→−− 2SO3(g)
Absorption of SO3in H2SO4 to give oleum (H2S2O7)
SO3 + H2SO4(dil) → H2S2O7 (Oleum)
Oleum is diluted with water to form H2S04
H2S2O7+ H2O → 2H2SO4

Answer 26:
Ferrimagnetism is observed when the magnetic moments of the domains in the sub-stances are aligned in parallel and antiparallel directions in unusual numbers. They are weakly attracted by magnetic field as compared to ferromagnetic substances.
Paramagnetic substances are weakly attracted by a magnetic field. They are magnetised in a magnetic field in the same direction. They lose their magnetism in they absence of magnetic field. Paramagnetism is due to presence of one or more unpaired electrone which are attracted by the magnetic field.
Ferrimagnetic substance lose ferrimagnetism on heating and become paramagnetic.

Answer 27:
Plus Two Chemistry Model Question Papers Paper 5 A27
b. The chromate and dichromateions are interconvertible in aqueous solution depending upon the pH of the solution
Plus Two Chemistry Model Question Papers Paper 5 A27A
Acidified potassium dichromate will oxidise iodides to iodine sulphides to sulphur.
tin (II) to tin (iv) and iron (ii) salt to iron (iii)
Plus Two Chemistry Model Question Papers Paper 5 A27B

Answer 28:
a. It is also called gravity separation. It is based on the difference in densities (gravities) of ore and the gangue. Ore is washed with stream of water so that light impurities are washed away, eg., haematite.
b. It is based on the principle that the im-purities are more soluble in the melt than in the solid state of metal.
Plus Two Chemistry Model Question Papers Paper 5 A28
The impure metal is heated with the help of a circular mobile heater at one end. This results in the formation of a molten zone. As the heater is moved along the rod, pure metal crystallises out of the melt and impurities pass onto the adjacent molten zone. This is reimpurities at one end of the rod is cut off and discarded.

  •  Metals like Si, Ge, Ga, B etc are refined by this method (semi-conductors and metals of high purity).

c. It is a process in which an ore is heated in regular supply of air at a temperature below the melting point of the metal so as to convert the give ore into oxide ore.
2ZnS + 3O2 → 2ZnO + 2SO2
Plus Two Chemistry Model Question Papers Paper 5 A28

Answer 29:
a. Aldehydes and ketones having at least one α hydrogen undergo a reaction in the presence of dilute alkali as catalyst to form β – hydroxy aldehydes (aldol) or β hydroxy ketones (ketol), respectively. This is known as aldol reaction. The aldol and ketol readily lose water to give α, β – unsaturated carbonyl compounds which are aldol condensation products and the reaction is called aldol condensation
Plus Two Chemistry Model Question Papers Paper 5 A29

b. Strong oxidising agents oxidise tolerene and derivatives to benzoic acids. How-ever, it is possible to stop the oxidation at the aldehyde stage with suitable reagents that convert the muthyl group to an inter¬mediate. Chromy chloride (CrO2Cl2) oxidise methyl group to a chromium complex, which on hydrolysis gives corresponding benzaldehyde.
Plus Two Chemistry Model Question Papers Paper 5 A29a
This reaction is called Etard reaction

c. Acyl chloride (acid chloride) is hydrogenated over catalyst, palladium on burium sulphate. This reaction is called Rosenmund reduction.
Plus Two Chemistry Model Question Papers Paper 5 A29b

Answer 30:
Kolbe’s reaction : Phenoxide ion generated by treating phenol with sodium hydroxide is even more reactive than phenol towards electrophilic aromatic substitution. Hence if undergoes electrophilic substitution with CO2, a weak electrophite. Ortho hydroxybenzoic acid is formed as the main reaction product.
Plus Two Chemistry Model Question Papers Paper 5 A30

Answer 31:
Fuel Cells: They produce electrical energy directly from the combustion of fuels such as hydrogen. carbon monoxide or methane. It is a Galvanic cell.
Plus Two Chemistry Model Question Papers Paper 5 A31
The electrode reactions of the most popular fuel cell H2– O2 cell is given below:
Plus Two Chemistry Model Question Papers Paper 5 A31A

Advantages:

  • PoHution-free.
  •  High efficiency (70%).
  • Continuous source of energy if gas supply ‘s maintained.
  •  The electrodes used in fuel cells are not affected during its working.

Answer 32:
[C0F6]3Here cobalt is in the +3 oxidation state.
Plus Two Chemistry Model Question Papers Paper 5 A32
But F is a weak ligand. So pairing does not take place. Hence in metal ion under goes sp3d2 hybridisation. There are four unpaired electrons present, therefore the complex is paramagnetic.

Answer 33:
a. When hydration of propene in the presence of dilute sulphuric acid. If gives
Plus Two Chemistry Model Question Papers Paper 5 A33
Plus Two Chemistry Model Question Papers Paper 5 A33a
The grignard reagents (R-Mg -X) react with compounds containing |C| = o to form addition compounds, which on hydrolysis with dil acid give the corresponding alcohols.Methanal react with grignai reagent to give a primary alcohol.

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