Plus One Chemistry Model Question Paper 3

Kerala Plus One Chemistry Model Question Paper 3

Time Allowed: 2 hours
Cool off time: 15 Minutes
Maximum Marks: 60

General Instructions to candidates

• There is a ‘cool off-time’ of 15 minutes in addition to the writing time.
• Use the ‘cool off time’ to get familiar with questions and to plan your answers.
• Read the instructions carefully.
• Read questions carefully before answering.
•  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.

Answer all questions from question numbers 1 to 7. Each carry one score.

Question 1:
The number of protons, electrons and neutrons in a species are equal to 17, 18 and 18 respectively. Which of the following will be the proper symbol of this species?

Question 2:
One-half of the difference between the number of electrons in the bonding and antibonding molecular orbitals is called …………

Question 3:
Name the phenomenon behind clean sing action of soap.

Question 4:
Name the process used for the industrial preparation of sodium carbonate,

Question 5:
In the Lassaigne’s test for halogens, they are precipitated as ……………….

Question 6:
Write the name of any one salt responsible for the permanent hardness of water.

Question 7:
Give the IUPAC name of the following compound: CH₃ CH₂ CO CH₂ CH₂ COOH

Answer any ten from question numbers 8 to 20. Each carries two scores.

Question 8:
Classify the following into intensive and extensive properties.
i. Internal energy
ii. Density
iii. Heat capacity
iv. Temperature.

Question 9:
Given the redox reaction:
CuO (s) + H₂ (g) → Cu (s) + H₂0 (g)
i. Identify the species which undergo reaction and which undergo oxidatlon.1
ii. Identify the reductant and oxidant in the above reaction.

Question 10:
Match the following :

Question 11:
Give the IUPAC name of the following compounds.

Question 12:
Give the name of the modified form of ideal gas equation and write down it.

Question 13:
Carbon has many allotropes.
a. Write the name of any two allotropic forms of carbon.
b. CCl₄ does not undergo hydrolysis. Give a reason.

Question 14:
i. Give the Arrhenius concept about acids and bases.
ii. Give one example each for Arrhenius acid and base.

Question 15:
When Sodium metal dissolves in liquid ammonia, it gives a deep blue coloured solution. Explain the reason.

Question 16:
A neon dioxygen mixture contains 70.6 g dioxygen and 167.5 g neon. If the pressure of the mixture of gases in the cylinder is 25 bar, what are the partial pressures of O₂ and neon in the mixture?

Question 17:
Write the difference between extensive and intensive properties. Give one example of each.

Question 18:
Fluorine reacts with ice as given below.
H₂O(s) + F₂(g) → HF (g) + HOF (g)
Justify that this is a redox reaction.

Question 19:
a. H₂O₂ is a bleaching agent. Why?
b. Complete the following reaction?
Zn (s) + NaOH (aq) → …………………..

Question 20:
Complete the following chemical reactions:

Answer any seven from question numbers 21 to 29. Each carries three scores.

Question 21:
In redox reactions, oxidation and reduction occur simultaneously.
a. How are oxidation and reduction related
to the oxidation number?
b. During a group discussion, one of your friends argues that thermal decomposition of KC/O₃ is a redox reaction while that of CaCO₃ is not a redox reaction. Give your opinion and substantiate.

Question 22:
Give the IUPAC names of the following compounds:

Question 23:
When some sodium acetate is added to a solution of acetic acid, the concentration of unionzed acetic acid increases.
a. What is the phenomenon involved? Substantiate.
b. Consider the equilibrium,

The solubility of AgCl is 1.06 x 10^-5 mol/L at 298 K. Find out its K_sp at this temperature.
c. What happens to the value of solubility and solubility product when HCI is passed through an AgCl solution?

Question 24:
Atmospheric pollution increases the global average temperature and the phenomenon is called global warming.
a. What are the major gases which contribute to wards global warming?
b. What can we do to reduce global warming?

Question 25:
The solubility product of Al(OH)₃ is 1 x 10³⁶ Calculate the solubility of Al(OH)₃

Question 26:
Account for the following :
i. Ionization enthalpy of Nitrogen is greater than that of Oxygen.
ii. 2^nd period elements show anomalous behaviour.

Question 27:
a. Give any two factors influencing the formation of an ionic bond.
b. Give the shape of the following species.
i. NH₄⁺
ii. HgCl₂

Question 28:
Redox reactions can be considered as electron transfer reactions. In an experiment a copper rod is dipped in AgNO₃ solution.
a. What happens to the colour of the solution and why?
b. Identify the oxidizing and reducing agent in this reaction.
c. Calculate the oxidation number of Cr in
K₂Cr₂O₇ and P in H₂P₂O₅.

Question 29:
a. 1-alkynes are weakly acidic in nature.
Give any two reactions to showthe acidic character of ethyne.
b. From the following, select the one in which Markownikoffs rule is best applicable.

Answer any three from question numbers 30 to 33. Each carries four scores.

Question 30:
The enthalpy change in a process is the same, whether the process is carried out in a Single step or in several steps.
a. Identify the law stated here. 1
b. Calculate the enthalpy of formation of CH4 from the following data:

Question 31:
a. When nitrogen and hydrogen combines to form ammonia, the ratio between the volumes of gaseous reactants and products is 1:3:2. Name the law of chemical combination illustrated here.
A compound is made up of two elements A and B, has A= 70%, B= 30%. The relative number of moles of A andB in the compound are 1.25 and 1.88 respectively. If the molecular mass of the compound is 160, find the molecular of the compound.

Question 32:
Phenol exhibit resonance.
i. Draw the resonance structures of phenol.
ii. Predict the directive influence of -OH group in Benzene ring.

Question 33:
a. Hydrogen peroxide restore the colour of lead paintings. Give a reason.
b. How does the atomic hydrogen torch function for cutting and welding purposes?

Answers

Answer 1:
\(_{ 17 }^{ 35 }{ Cl }\)

Answer 2:
Bond order

Answer 3:
Surface tension.

Answer 4:
Solvay process.

Answer 5:
Silver halides.

Answer 6:
CaCl₂ or MgSO₄

Answer 7:

Answer 8:
Extensive properties: Internal energy, Heat capacity.
Intensive properties: Density, Temperature.

Answer 9:
i. Reduction species – CuO
Oxidation species – H₂
ii. Reductant- H₂, Oxidant – CuO

Answer 10:

Answer 11:
11. i. 3 – chloropropanal
ii. 3 – methylpentanenitrite.

Answer 12:
There is deviation from ideal behaviour at high pressure and low temperaure. This is due to two faulty assumptions in kinetic theory of gases. It is corrected by van der Waal’s equation.

where n is the number of moles of the gas a and b are van der Waal’s constants.

Answer 13:
a. Diamond, graphite, fullerene
b. This is due to the absence of vacant d- orbitals in carbon.

Answer 14:
i. Acid is a substance which dissociate to give H⁺ ion in aqueous solution. Base is a substance which dissociate to give OH^– ion in aqueous solution.
ii. HCl, H₂SO₄, CH₃COOH etc are acids which give free H⁺ ions in aqueous solution.

Answer 15:
Blue colour H₂ gas is evolved during the process. If M is alkali metal.

Blue colour due to the ammoniated electron which absorbs energy.

Answer 16:

Answer 17:
Extensive – Depends on the quantity of matter, eg., internal energy, heat capacity enthalpy volume, mass etc.
Intensive – Does not depend on the quantity of matter, eg., Density, S.T.P, T, etc.

Answer 18:
Oxidation number of fluorine decreases in HF while the oxidation no. of fluorine in-creases in HOF. So it is a redox reaction.

Answer 19:
a. H₂O₂ decomposes to release nascent oxygen that oxidises the colouring matter to colourless.
b. Zn(s)+2NaOH(aq) → Na₂ZnO₂(aq) +H₂(q)

Answer 20:

Answer 21:
a.Oxidation is a process which involves an increase in oxidation number of an element.
Reduction is a process which involves a decrease in oxidation number of an element.
IMG
The reaction (1) is a redox reaction because there is a change in oxidation state. But (2) is not a redox reaction because there is no change in oxidation state.

Answer 22:
a. 5, 5 -dimethyl heptan – 2 – ol
b. 2 – pentanone
c. 2, 4, 6 – tribromophenol.

Answer 23:
a. Common ion effect. It the suppression of dissociation of weak electrolyte
(CH₃COOH) by addition of a salt containing common ion (CH₃COONa).
IMG
c. When HCI gas is passed through AgCl solution. Solubility of AgCI decreases while the solubility product does not change.

Answer 24:
a. CO₂, methane, chlorofluoro carbons etc are the major gases which contribute to- wards global warming.
b. 1. Minimise the use of automobiles.
2. Plant more trees.
3. Avoid burning of dry leaves, wood.

Answer 25:

Answer 26:
i. because of the half filled electronic configuration of N. (N = 1s² 2s² 2p³)
ii. due to their small size, high electrone gativity and ionisation enthalpy,large charge/radius ratio and due to the absence of vacant d-orbitals.

Answer 27:
a. Low ionisation enthalpy of the electropositive atom (metal atom).
High negative electron gain enthalpy of the electronegative atom (non-metal atom)
High lattice enthalpy of the ionic compound formed.
i. NH⁴⁺ – Tetrahedral
ii. HgCl² – Linear

Answer 28:
a. The solution becomes blue colour due to the formation of Cu²⁺ ions.
b. Ag⁺ (AgNO₃) is the oxidising agent and Cu is the reducing agent.
c. Oxidation number of Cr in K₂Cr₂O₇ is +6 and P in H₂P₂O₅ is +4.

Answer 29:
a. Ethyne reacts with sodium ethynide and liberate H₂. It reacts with sodamide (NaNH₂) to form sodium ethynide and liberate ammonia.

Answer 30:

Answer 31:
a. Gay – Lussac’s law of Gaseous volumes
b. The relative number of moles means % / atomic mass

Element	%	Relative no.of moles	Simple ratio	Simplest whole no.ratio
A	70	1.25	1.25/1.25= 1	2
B	30	1.88	1.88/1.25 = 1.5	3

Empirical formula is A₂B₂
Atomic mass of A = % / no.of moles = 70 / 1.25 = 56
Atomic mass of B = % / no.of moles = 30/ 1.88 = 15.96
So, emp. Formula mass = 56 x 2 + 15.96 x 3 = 159.88 = 160
n = mol. mass / emp.Formula mass = 160/160 = 1
Molecular formula = (emp.Formula)n = (A₂B₃)X 1 = A₂B₃

Answer 32:

ii. -OH group is an ortho-para directing group.

Answer 33:
a. This is due to the oxidising action of H₂O₂.

b. Here H atoms are allowed to recombine on the surface to be welded to generate the temperature of 4000K.

Plus One Chemistry Previous Year Question Papers and Answers