Kerala Plus One Chemistry Question Paper March 2020 with Answers

Reviewing Kerala Syllabus Plus One Chemistry Previous Year Question Papers and Answers Pdf March 2020 helps in understanding answer patterns.

Kerala Plus One Chemistry Question Paper March 2020

PART – A

Answer any 7 questions from 1 to 9. Each carries 1 score. (7 × 1 = 7)

Question 1.
Water gas is a mixture of
(a) CO + H₂
(b) CO + N₂
(c) CO₂ + H₂
(d) CO₂ + N₂
Answer:
(a) CO + H₂

Question 2.
The element that has outer electronic configuration 3d54s1 belongs to
(a) s-block
(b) p-block
(c) d-block
(d) f-block
Answer:
(c) d-block

Question 3.
The number of radial nodes of 4p orbital is
(a) 1
(b) 2
(c) 3
(d) 4
Answer:
(b) 2 (n – l – 1)

Question 4.
The species that can form both conjugate acid and conjugate base among the following is
(a) H₂O
(b) BF₃
(c) HCl
(d) CO₂
Answer:
(a) H₂O

Question 5.
Liquids having larger difference in boiling points are separated by
(a) Distillation
(b) Fractional distillation
(c) Steam distillation
(d) Vacuum distillation
Answer:
(a) Distillation

Question 6.
The oxidation number of an atom in the elementary form is ………….
Answer:
Zero

Question 7.
The unit of coefficient of viscosity in c.g.s. system is
Answer:
Poise or gcm^-1S^-1

Question 8.
The class of organic compound differe by a group between adjacent members are called
Answer:
Homologous series

Question 9.
The combination of smoke and fog is known as ……….
Answer:
Smog

PART B

Answer any 10 questions from 10 – 22. Each carries 2 scores. (10 × 2 = 20)

Question 10.
(a) Classify the following matter as homogenous mixture, heterogenous mixture, element and compounds. (1)
Answer:
Homogenous mixture – air
Heterogenous mixture – Muddy water
Element – gold Compound – water

(b) Define limiting reagent of a reaction. (1)
Answer:
Limiting reagent is that reagent which is completely used up in the reaction.

Question 11.
Write any two characteristic properties of canal rays. (2)
Answer:
1. They move in straight line
2. They affect photographic plate

Question 12.
(a) Identify the group and period of an element having atomic number (Z) 25 in the periodic table. (1)
Answer:
Period – 4, Group – 7

(b) Predict the formula of the stable binary com-pound that would be formed by the combination of the following pairs of elements: (1)
(i) Lithium and Oxygen
(ii) Aluminium and iodine
Answer:
(i) Li₂O
(ii) AlI₃

Question 13.
Explain the general periodic trend of first ionization enthalpy along a period and group in the periodic table. (2)
Answer:
In a period as we move from left to right first ionisation enthalpy increases. In a group as we move down first ionisation energy decreases.

Question 14.
A gas occupy 400ml volume at 47°C and 800mm of Hg pressure. What will be its pressure at a height where the temperature is 27°C and volume of the gas is 450ml? (2)
Answer:

Question 15.
Define extensive and intensive properties. Give examples for each. (2)
Answer:
Extensive properties are properties which depend upon mass.
eg: mass, volume, internal, energy, enthalpy heat capacity.

Intensive properties are properties which are independent of mass.
eg: Temp, density, pressure

Question 16.
Derive the relation between equilibrium constants K_c and K_p for a general reaction.
at equilibrium. (2)
Answer:

Question 17.
(a) What are saline hydrides? (1)
Answer:
Saline hydrides or ionic hydrides are formed by the reaction of Hydrogenation with first or second group elements, ie. alkali metals and alkaline earth metals.

(b) Why hard water is unsuitable for laundry pur-pose? (1)
Answer:
It does not form lather with soap.

Question 18.
List any two points of difference between Lithium and other alkali metals. Give reasons. (2)
Answer:
Li is harder.
Li can form monoxide

Question 19.
(a)What is borone bead test? (1)
Answer:
On heating Borax first loses water molecules and swells up. On further heating it turns into a transparent liquid which solidifies into glass like material known as borax bead.

(b) SiCl₄ can be hydrolysed but CCl₄ cannot. Why? (1)
Answer:
In CCl₄ there is no vacant d orbitals. So it cannot be hydrolysed. But in Si; there are vacant d orbitals.

Question 20.
(a) Why AlCl₃ exist as dimers? (1)
Answer:
AlCl₃ is an electron deficient compund and is unstable. So it forms dimer.

(b) Write the basic structural unit of silicons and silicates.
Answer:
Silicone – (R₂SiO)_n
Silicates – SiO^4-

Question 21.
Give the complete and bondline structure of pent-e-en-2-ol. (2)
Answer:
Structure Formula

Question 22.
Drawnttiei Newman projections for staggered and eclipsed conformations of ethane. (2)
Answer:
Structure Formula

Answer any 7 questions from 23 – 31. Each carries 3 scores. (7 × 3 = 21)

Question 23.
(a) Hydrogen and Oxygen combines to form H₂O and H₂O₂. Which law of chemical combination is illustrated here? (1)
Answer:
Law of multiple proportion.
When two elements combine to form more than one compound the fixed masses of element combine with the other bear a simple whole no. ratio.

(b) The balanced chemical equation for combustion of CH₄ is
CH_4(g) + 2O_2(g) → CO_2(g) + 2H₂O_(l)
Calculate the amount of water formed by the combustion of 32g of CH₄? (2)
Answer:

Question 24.
(a) Give two examples of compounds having expanded octet. (1)
Answer:
PCl₅, SF₆

(b) Draw the Lewis dot symbols of (2)
(i) Cl₂
(ii) NF₃
Answer:

Question 25.
(a)Write the name of Van der Waal’s force between (1)
(i) Non-polar molecules.
(ii) Molecules having permanent dipoles.
Answer:
1. London forces
2. Dipole – Dipole interaction

(b) State Dalton’s law of partial pressures. (1)
Answer:
Total pressure exerted by a mixture of non reactive gases is equal to the sum of partial pressures of the individual gases.

(c) At higher altitudes, pressure cooker is used for cooking. Give Reasons. (1)
Answer:
At higher altitudes atmospheric pressure is very low. Water boils at low temp.

Question 26.
(a) Write the mathematical expression of First Law of thermodynamics.
Answer:
∆U = q + w

(b) Define standard enthalpy of formation. (1)
Answer:
It is the enthalpy change when one mole of a compound is formed from its constituent efements in their standard state.

(c) Write the condition of temperature for a process to be spontaneous whose ∆H and ∆S values are positive. (1)
[Hint: ∆G = ∆H – T∆S]
Answer:
∆H – T∆S = ∆G
For a process to be spontaneous ∆G should be negative.
If ∆H & ∆S are positive ∆G is negative only at high temperature

Question 27.
(a) Justify that the following reaction is a redox reaction.
H₂S_(g) + Cl_2(g) → 2HCl_(g) + S_(s) (2)
Answer:

Sulphur gets Oxidised and Cl₂ gets redused.
Both oxidation and reduction occurs.

(b) Write the Stock notation of MnO₂. (1)
Answer:
Mn(IV)O₂

Question 28.
(a) What is calogen? (1)
Answer:
Calgon – Sodium hexametaphosphate

(b) Explain the methods used for the removal of temporary hardness of water. (2)
Answer:
Boiling – Hard water is boiled and the precipitate is filtered.
Clark process – Calculated amount of Ca(OH)₂ is treated with hard water.

Question 29.
(a) What is the purpose of adding gypsum during the manufacture of cement? (1)
Answer:
To decrease the setting time of cement

(b) Match the following.
Tablee
Answer:
Tablee

Question 30.
(a) What is Lindlar’s catalyst?
Answer:
Partially deactivated palladised charcoal.

(b) Identify A, B and C.

Answer:

(c) Complete the following reaction:

Answer:

Question 31.
Define the following terms:
(i) Freons
(ii) BOD
(iii) Green house effect, nnalmoyon (oiisonio
Answer:
(i) Freons – Chlorofluorocarbons

(ii) BOD – Biochemical oxygen demand
The amount of oxygen required to degrade organic matter.

(iii) Green house effect
When number of the trees in the earth decreases, the amount of CO₂ in the earth increases. As a result temperature in the earth increases. Because of this ice burgs melts and seal level rises. This is known as Green House Effect.

Answer any 3 questions from 32 – 35. Each carries 4 scores. (3 × 4 = 12)

Question 32.
(a) Write the n and I values of a 4d electron. (1)
Answer:
n = 4, l = 2

(b) Give the names of series of spectral lines of atomic hydrogen and their region in the electro¬magnetic spectrum. (2)
Answer:
(b) Lyman – u.v.
Balmer – Visible
Paschen – IR
Bracket – IR
Pfund – IR

(c) State Hund’s rule of maximum multiplicity. (1)
Answer:
Pairing occurs only after all the degenerate orbitals are completely half filled.

Question 33.
(a) Predict the hybridisation of phosphorous atom in PCl₅ molecule. (1)
Answer:
PCl₅ – sp³d

(b) Account for the high reactivity of PCl₅ molecule. (1)
Answer:
In PCl₅ there are two types of bonds. (1) Two axial bonds and 3 equatorial bonds.
Axial bonds are longer and are more reactive.

(c) Draw the MO energy level diagram of O₂ molecule. (2)
Answer:

BO = ½(nb – na)
= ½(10 – 6) = 2

Question 34.
(a) Predict the nature of solution produced by the hyrolysis of sodium acetate. (1)
Answer:

(b) Calculate the pH of a solution having H⁺ ion concentration 3.8 × 10³ m. (2)
Answer:
pH = -log[H⁺] = -log(3.8 × 10^-3)

(c) Explain the effect of pressure in the following equilibrium using Le Chatelier principle:

Answer:
Co + 3H₂ → CH₄ + H₂O
No.of moles of reactants is more than no.of moles of product. So high pressure is favoured.

Question 35.
(a) Write the IUPAC name of

Answer:

(b) Write the functional isomers of molecule having molecular formula C₃H₆O. (1)
Answer:

(c) How will you detect the presence of chlorine in an organic compound using Lassigne’s test.(1)
Answer:
A little of the salt is mixed with metallic sodium in an ignition tube and heated. When it becomes red hot it is plunged into water taken in a China dish boiled and filtered. This is known as Lassaignes extract.

A little of the Lassaigne’s extract is acidified with dil. HNO₃ and 1 ml AgNO₃ is added white ppt is obtained. This white ppt indicates presence of chloride ion.