Kerala SSLC Chemistry Previous Year Question Paper March 2019 English Medium

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Kerala SSLC Chemistry Previous Year Question Paper March 2019 English Medium

General Instructions:

1. The first 15 minutes is the cool off time. You may use the time to read and plan your answers.
2. Answer the questions only after reading the instructions and questions thoroughly.
3. Questions with marks series 1, 2, 3 and 4 are categorized as sections A, B, C and D respectively.
4. Five questions are given in each section. Answer any four from each section.
5. Answer each question by keeping the time.

Section – A

(Answer any 4 questions from 1 to 5. Each question carries 1 score) (4 × 1 = 4)

Question 1.
Which of the following molecule can undergo addition reaction? (1)
(methane, ethane, propene, butane)
Answer:
Propene

Question 2.
The glass used to make lenses and prisms is ………(1)
Answer:
Flint glass / optic glass/ Lead glass

Question 3.
Atomic mass of Nitrogen is 14. which of the following sample contain 6.022 x 10²³ Nitrogen atoms? (1)
(7g Nitrogen, 14 g Nitrogen, 28g Nitrogen, 1g Nitrogen)
Answer:
14g nitrogen

Question 4.
The ore of a metal is lighter than the impurities. Which method is suitable for its concentration? (1)
Answer:
Froth floatation process

Question 5.
A fresh piece of Mg ribbon loses its luster after a few days. This is due to the formation of the compound ………..(1)
Answer:
Magnessium oxide/MgO/oxide

Section – B

(Answer any 4 questions from 6 to 10. Each question carries 2 scores)(4 × 2 = 8)

Question 6.
The last subshell of an element is 3p and there are 3 electrons in it.
a) Write the complete electronic configuration of the element. (1)
b) Identify its period and group. (1)
Answer:
a) 1s² 2s² 2p⁶ 3s² 3p³ (2, 8, 5)
b) Period -3 group -15

Question 7.
An iron nail is dipped in CuSO₄ solution. (Reactivity order Fe>Cu)
a) What is the change that can be noticed on the iron nail after a while? (1)
b) Write down the chemical equation of the oxidation reaction occurs here. (1)
Answer:
a) Copper gets deposited on iron nail b) Fe → Fe²⁺ + 2e^–

Question 8.
4g of NaOH is dissolved in water and the volume is made upto 1 L.
(1 mole of. NaOH = 40 g)
a) Calculate the molarity of the resultant solution. (1)
b) How will you make 1 M solution of NaOH using the same amount (4g) of NaOH? (1)
Answer:
a) Molecular mass of NaOH = 23 + 16 + 1 = 40

b) Dissolve 4g NaOH in water and make up the solution in to 100 mL

Question 9.
Concentrated Cu₂S is converted into oxide by roasting.
a) Write the process of roasting. (1)
b) How impurities like sulphur and phosphorus are removed in this process? (1)
Answer:
a) Heating the ore in the presence of air below its melting point.
b) Sulphur and phosphorous are removed as their oxides

Question 10.
Ethanoic acid is an organic compound having industrial values.
a) How ethanoic acid is manufactured industrially?^)
b) Give any one use of ethanoic acid. (1)
a) Ethanoic acid is manufactured by reacting methanol and carbon monoxide in the preence of a catalyst.

b)

• Production of rayon
• In rubber and silk industry
• To produce vinegar

Section – C

(Answer any 4 questions from 11 to 15. Each question carries 3 scores) (4 × 3 = 12)

Question 11.
H₂(g) + I₀2(g) ⇌ 2HI_(g)
a) What is the total number of moles of reactants and products in the above reaction. (1)
b) What is the effect of pressure in this reversible reaction? Explain. (2)
Answer:
a) No. of mol of reactants = 2
No. of mol of products =2
b) Pressure has no effect on this reaction. Because there is no change in volume (no.of molecules) due to forward and backward reactions.

Question 12.
The structure of a hydrocarbon is given below:

a) How many C-atoms are there in the main chain?
Which is the word root? (1)
b) Identify the branch and its position number (1)
c) Write the IUPAC name of this compound. (1)
Answer:
a) 5, pent
b) Methyl, 3
c) 3-methyl pentane

Question 13.
The chemical equation for the manufacture of ammonia is N₂(g) + 3H₂(g) → 2NH₃(g)
a) Complete the following: 1 mol N₂ + …………H₂→ …………NH₃ (1)
b) Calculate the amount of H₂ required to rea.ct with 28 g of N₂ completely. (1)
[Hint: Molecular mass of N₂ = 28, H₂ = 2]
c) What will be the volume of NH₃ formed at STP, if 22.4L of N₂ is completely reacted? (1)
Answer:
a) 1 mol N₂ + 3mool -H₂ → 2 mol NH₃
b) 28 g N2 requires 3 mol H₂
3 mol H₂ = 3 x 2 = 6g
c) NH₃ formed when 1 mol (22.4L)
N₂ reacts = 2 mol
Volume of 2 mol NH₃ at STP = 2 x 22.4 = 44.8L

Question 14.
Consider the metals and solutions given in the box.
Zn, Mg, Cu, Ag, CuSO₄ solution, MgSO₄ solution
a) Which of the above metals are to be selected to construct a Galvanic cell? (1)
b) Identify the anode and cathode of the cell. (1)
[Hint: Reactivity order Mg > Zn > Cu > Ag]
c) Write the redox reaction taking place in this cell. (1)
Answer:
a) Mg, Cu
b) Anode Mg/MgSO₄
Cathode Cu/CuSO₄
c)

Question 15.
Alumina is mixed with cryolite and subjected to electrolysis to extract aluminium.
a) Why cryolite is added to alumina? (1)
b) Which are the ions present in alumina? (1)
c) Write the equation of the reduction reaction taking place at negative electrode. (1)
Answer:
a) To lower the melting point of alumina and to increase the electrical conductivity.
b) Al³⁺, O^2-
c) Al³⁺ + 3e^– → Al

Section – D

(Answer any 4 questions from 16 to 20. Each question carries 4 scores)(4 × 4 = 16)

Question 16.
Zinc piece and zinc powder are taken in two test tubes and equal’amount of dil. HCl is added.
a) In which test tube does the reaction proceed faster? (1)
b) Give the reason. (2)
c) Give an instance from daily life, where such condition is made use. (1)
Answer:
a) In second test tube (Zinc powder)
b) Total surface area increases on powdering. So the rate of effective collisions increases.
c) • Fire wood catches fire quickly if splitted up into small pieces.
• Vegetables get cooked easily if cut into small pieces.
• Condiments are powdered for quick action.

Question 17.
The structure of two organic compounds are given below:
i) CH₃-CH₂-CH₂-CH₂-OH
ii) CH₃-CH₂-0-CH₂-CH₃
a) Write the molecular formula of these com-pounds. (1)
b) Which type of isomerism do they exhibit? (1)
c) Explain this isomerism. (1)
d) Write the strucutral formula of a position isomer of compound (i) (1)
Answer:
a) C₄H₁₀O
b) Functional group isomerism
c) Compounds having same molecular formula and different structural formula and functional groups are called functional group isomers.
d)

Question 18.
The atomic number of an element is 19.
a) Write the subshell electronic configuration. (1)
b) Identify its group, period, block and oxidation state. (2)
c) Write any one characteristic of the block to which the element belongs., (1)
Answer:
a) 1 s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
b) Group -1 Period – 4
Block – s Oxidation state +1
c) Highly electropositive, low ionisation energy.

Question 19.
Two organic reactions are given below:

a) Identify the products A and B (1)
b) Which type of reaction is (i)? (1)
c) The product B has industrial values. Give its name and use. (2)
Answer:
a)

b) Substitution reaction
c) Poly Vinyl chloride (PVC)
PVC is a plastic used for thd manufacture of pipes hoses etc.

Question 20.

a) Give the functions of antipyretics and anti-biotics. (2)
b) Write any two unhealthy practices among people in using medicines. (2)
Answer:
a) Antipyretics – lowers body temperature
Antibiotics – Destroys harmful microbes and prevent their growth.

b)

• Self treatment
• Excessive use of medicine
• Using medicine prescribed for others
• Using old prescriptions for taking medicines
• Dont taking medicine at regular intervals.b