Kerala Plus Two Chemistry Model Question Paper 4
Time: 2 Hours
Cool off time: 15 Minutes
Maximum: 60 Scores
General Instructions to candidates
- There is a ‘cool off time’ of 15 minutes in addition to the writing time of 2 hrs.
- Use the ‘cool off time’ to get familiar with the questions and to plan your answers.
- Read questions carefully before you answering.
- Read the instructions carefully.
- Calculations, figures, and graphs should be shown in the answer sheet itself.
- Malayalam version of the questions is also provided.
- Give equations wherever necessary.
- Electronic devices except non-programmable calculators are not allowed in the Examination Hall.
(Questions 1 to 7): Carry one score each. Answer all questions.
Question 1.
Saline water is a solution.
a. Isotonic
b. Hypertonic
c. Hypotonic
d. Heavy water
Question 2.
Name the law which states that partial pressure of a gas is directly proportional to its mole fraction.
Question 3.
A crystalline solid
a. changes abruptly from solid to liquid
b. has no definite melting point
c. Undergoes deforestation of its geometry easily
d. has an irregular 3dimensional arrangement.
Question 4.
Galvanization of iron denotes coating with
a. Al
b. Sn
c. Cd
d. Zn
Question 5.
Write an example of an emulsion.
Question 6.
The formation of micelles takes place on above
a. Inversion temperature
b. Boyle temperature
c. Critical temperature
d. Kraft temperature
Question 7.
Complete the reaction.
(Questions 8 to 20) : Answer any ten. Each questions carries two scores.
Question 8.
Vapour pressure of a solution is different from that of the pure solvent.
i. Name the law which helps us to determine partial vapour pressure of a volatile component in solution.
ii. State the above law?
Question 9.
Zero-order reaction means that the rate of a reaction is independent of the concentration of reactants.
i. Write an example of a zero order reaction.
ii. Write the integral rate expression for the zero order reaction, R → P
Question 10.
a. How will you distinguish primary and secondary alcohols using Luca’s test?
b. Write the correct pair of reactants for the preparation of butyl ethyl ether by Williamson synthesis.
Question 11.
Two chemical reactions are given below:
1. Identify the products of each reaction.
2. Give the name of each reaction.
Question 12.
200 cm3 of an aqueous solution of a protein contains 1.26 g of protein. The osmotic pressure of a solution of 300 K is found to be 8.3 × 10-2 bar. Calculate the molar mass of protein. (R= 0.083 L bar K-1 mol-1)
Question 13.
i. The number of moles of the solute per kilogram of the solvent is
a. Mole fraction
b. Molality
c. Molarity
d. Molar mass
ii. ‘The extent to which a solute is dissociated or associated can be expressed by Can’t Hoff factor.’ Substantiate the statement.
Question 14.
Presence of excess sodium makes NaCl crystal coloured. Explain on the basis of crystal defects.
Question 15.
Explain the following:
i. Esterification
ii. Williamson Synthesis
Question 16.
Aldehydes, Ketones and Acids contain
a. Name the product obtained by the reaction between Acetic acid and Ethanol.
b. Give any two tests to distinguish between aldehydes and ketones.
Question 17.
a. Among the following which is not a colligative property?
i. Osmotic pressure
ii. Bevation of boiling point
iii. Vapour pressure
iv. Depression of freezing point
b. What is the significance of Can’t Hoff factor?
Question 18.
One of the fuel cells uses the reaction of hydrogen and oxygen to form water. Write down the cell reaction taking place in the anode and cathode of that fuel cell.
Question 19.
The vapour pressure of pure benzene at a certain temperature is 0.850 bar. A non-volatile, nonelectrolyte solid weighing 0.5g when added to 39 g of benzene (molar mass 78 g/mol), vapour pressure becomes 0.845 bar. What is the molar mass of the solid substance?
Question 20.
a. Write down the ionization isomer of [CO(NH3)5Cl] SO4
b. Write the IUPAC name of the above compound.
(Questions 21 to 29): Answer any seven. Each question carries three scores.
Question 21.
i. Which of the following oxidation state is ! not shown by Manganese?
a. + 1
b. +2
c. +4
d. +7
ii. Represent the structure of dichromate ion.
iii. Potassium permanganate (KMnO4) is a strong oxidizing agent. Write any two oxidizing reactions of KMnO4.
Question 22.
Account for the following:
i. H2O is a liquid while H2S is a gas.
ii. Noble gases have very low boiling points.
iii. NO2 dimerises to N2O4.
Question 23.
How will you bring below the following conversions? (Write the chemical equations)
i. Ethanol → Ethanoic acid
ii. Benzamide → benzoic acid
iii. Benzaldehyde → meta nitro benzaldehyde
Question 24.
Amines are classified as primary, secondary and tertiary.
a. Write the IUPAC name of the following compound: NH2-(CH2)6 NH2
b. Which is stronger base CH3NH2 or C6H5NH2? Why?
Question 25.
a. Which named reaction is used to reduce CH3COCl to CH3CHO?
b. Aldehydes and Ketones undergo reactions due to the presence of hydrogen I atom.
i. Write the name of the reaction of aldehydes which take place only because of the presence of a hydrogen atom.
ii. How will you bring about the above reaction?
Question 26.
Amines are classified as a primary, secondary and tertiary amine.
a. How will you convert nitrobenzene to aniline?
b. Represent the structure of secondary and tertiary amine.
c. Aniline does not undergo Friedel Craft’s reaction. Why?
Question 27.
Nucleophilic substitution reactions are of two types of SN reactions and SN reactions,
a. Write any 2 differences between \({ S }_{ N }^{ 1 }\) and \({ S }_{ N }^{ 2 }\) reactions.
b. Write any 2 reasons for the less reactivity of aryl halides towards nucleophilic substitution reactions.
Question 28.
Primary, secondary and tertiary amines can be distinguished using Hinsberg’s reagent.
i. What is Hinsberg’s reagent?
ii. How will you distinguish primary, secondary and tertiary amines using Hinsberg’s reagent?
Question 29.
Schottky defects and Frenkel defects are two stoichiometric defects shown by crystals.
i. Classify the following crystals into those showing Schottky defects and Frenkel defects: NaCl, AgCl, CsCl, CdCl2
ii. Name a crystal showing both Schottky defect and Frenkel defect.
(Questions 30 to 33): Answer any three. Each question carries four scores.
Question 30.
a. Account for the following:
i. NH3 acts as a Lewis base.
ii. PCl3 fumes in moist air.
b.
i. Suggest any two fluorides of Xenon.
ii. Write a method to prepare any one of the above-mentioned Xenon fluorides.
Question 31.
Some elements in block show allotropy.
a. What are the allotropic forms of sulphur?
b.
i. How will you manufacture sulphuric acid by contact process?
ii. What is an interhalogen compound?
Question 32.
Potassium dichromate is an orange coloured crystal and is an important compound used as an oxidant in many reactions.
a. How do you prepare K2Cr2O7 from chromite ore?
b. How will you account for the colour of ! potassium dichromate crystals?
Question 33.
a. Most important chemical reactions of haloalkanes are their substitution reactions.
i. What is \({ S }_{ N }^{ 1 }\) reaction?
ii. Arrange the four isomeric Bromo butanes in the increasing order of their reactivity towards SN1 reaction.
b. How will you prepare chlorobenzene from benzene diazonium chloride?
Answers
Answer 1.
hypertonic
Answer 2.
Henry’s law
Answer 3.
a
Answer 4.
d
Answer 5.
MIlk
Answer 6.
d
Answer 7.
Bakelite
Answer 8.
i. Raoult’s law.
ii. For a solution of volatile liquids, the partial vapour pressure of each component ¡n the solution is directly proportional to its mole fraction of component in the solution.
Answer 9.
i. Decomposition of ammonia gas on a hot platinum surface.
ii. K = [R0]-[R]; where R0 is the initial concentration of the reactants, R is the concentration at a time and K is the rate constant.
Answer 10.
a. Alcohols are soluble in Lucas reagent and their halides are immiscible and form turbidity 3° alcohols produce turbidity immediately 2° alcohols produce turbidity within a few minutes whereas 1° alcohol does not produce turbidity at all at room temperature.
Answer 11.
2. Clemmensen reduction, Gattermann Koch reaction.
Answer 12.
Answer 13.
i. b. Molality
ii. In the case of dissociation, the observed molecular weight has a lower value than the normal molecular weight while in the case of an association, the observed molecular weight is higher than the normal molecular weight. In order to explain such j abnormal cases, Can’t Hoff factor is used. This factor is defined as
Answer 14.
Presence of excess sodium makes NaCl crystal coloured, this is caused by metal excess defect due to anionic vacancies. When NaCl crystal is heated in an atmosphere of sodium vapour, the sodium j atoms are deposited on the surface of the crystal and combine with Na atoms to give NaCl. The released electrons diffuse into the crystal and occupy an anionic site. As a result of the crystal now has an excess of sodium. The anionic sites occupied unpaired electrons are F centres. They impart a yellow colour to the crystals of NaCl.
Answer 15.
i. Alcohols and phenols react with carboxylic acids, acid chlorides and acid anhydrides to form esters.
ii. It is an important laboratory method for the preparation of symmetrical and unsymmetrical ethers. In this method, an alkyl halide is allowed to react with sodium alkoxide.
Answer 16.
a. Acetic acid and ethanol react in the presence of H2SO4/H2O to form ethyl acetate. This is called esterification.
b. Aldehydes answer Tollen’s test. On warming an aldehyde with Tollen’s reagent, a bright silver mirror is produced due to the formation of silver metal. Ketones do not answer this test, in presence of HCl.
Fehling’s test: Aldehydes on heating with Fehling’s solution give a reddish brown precipitate. Ketones do not answer this.
Answer 17.
a. Vapour pressure.
b. In the case of dissociation, the observed molecular weight has a lower value than the normal molecular weight while in the case of an association, the observed molecular weight is higher than the normal molecular weight. In order to explain such abnormal cases, Can’t Hoff factor is used.
Answer 18.
The electrode reactions are:
Answer 19.
Answer 20.
a. [Co(NH3)5SO4]Cl
b. Pentaamminesulphatocobalt (II) chloride
Answer 21.
Answer 22.
i. Due to the presence of H-bonding in between H2O molecule they exist as a liquid. But no such H bonding is there In H2S due to less electronegative nature and large size compared to oxygen.
ii. Noble gases being monoatomic have no interatomic forces except weak dispersion forces and therefore, they are liquefied at very low temperatures. Hence, they have low melting points.
iii. NO2 contains an odd number of valence electrons. It behaves as a typical odd molecule. On dimerisation, it is converted to stable N.O. molecule with an even number of electrons.
Answer 23.
Answer 24.
a. Hexane 1,6 diamine.
b. The stronger base is CH3NH2. Presence of + 1 group (CH3) increases the electron density on Natom and thus basicity increases.
Answer 25.
a. Rosenmund reduction.
b.
i. Aldol condensation.
ii. Aldehydes and ketones having at least one a hydrogen atom in presence of dilute alkali given hydroxy aldehydes.
Answer 26.
c. The catalyst in FriedalCraft’s reaction is any. AlCl3, it, is a Lewis acid so get coordinated with electron pair of N atom in aniline. So an electrophile cannot attack the ring.
Answer 27.
a.
| \({ S }_{ N }^{ 1 }\) | \({ S }_{ N }^{ 2 }\) |
| The rate of the reaction depends only on the molar concentration of the substrate. | Rate depends on the molar concentration of the alkyl halide and the OFF ions. |
| Takes place in two steps. | Takes place in a single step. |
b.
1) Aryl halides are electron rich.
2) In aryl halides, the halogen is attached to an sp2 hybridised C, which is highly stable.
Answer 28.
i. Benzene sulphonyl chloride.
ii. 1° amine react with Flinsberg’s reagent to form sulphonamides which is soluble in alkali. 2° amines react with Hinsberg’s reagent forming sulphonamides insoluble in alkali. 3° amines do not react with Flinsberg’s reagent.
Answer 29.
i. Schottky defect : NaCl, CsCl Frenkel defect: AgCl, CdCl2
ii. AgBr.
Answer 30.
a. i. The nitrogen atom in NFH3 has one lone pair of electrons which is available for donation. So it acts as a Lewis base,
ii. PCl3 undergo hydrolysis in presence of moisture giving fumes of HCl.
b.
Answer 31.
a. Rhombic sulphur or sulphur and monoclinic sulphur or p sulphur,
b.
i. Contact process.
Burning of sulphur in the air to generate SO2. Conversion of SO2 to SO3 by there action with oxygen in the presence of a catalyst (V2O5).
Absorption of SO3 in H2S04 to give Oleum. Oleum with water gives H2SO4.
ii. Halogens can react themselves to form binary compounds known as interhalogen compounds. They are more reactive than halogens because in the difference in electronegativity of the combining halogens.
Answer 32.
a. K2Cr2 O7 is prepared from chromite ore by heating with Na2CO3 in the presence of air when sodium chromate is formed.
The soluble Na2CrO4 on acidification with H2SO4 produces sodium dichromate which on treating with KCl gives potassium dichromate.
b. Coloured property of potassium dichromate is due to the presence of unpair electron when light falls on the compound the unpair electron undergoes dd electron transmission. This creates the colour for the potassium dichromate.
Answer 33.
a. i. First, the carbocation is formed (slow, rate determining) and then nucleophile attacks (fast). Order of reactivity of alkyl halides is 3°> 2° > 1 “(due to decreasing stability of carbocation). It results in racemization. ie., retention as well as inversion.
