MALAPPURAM DISTRICT HIGHER SECONDARY
CHEMISTRY TEACHERS ASSOCIATION
OXY CHEMISTRY 3.0
FIRST YEAR MODEL EXAMINATION 3.4 BASED ON FOCUS AREA 2021
ANSWER KEY
Time 2 hrs Cool Off Time : 20 minutes ( Maximum score 60 )
Answer any 6 questions from 1 to 12. Each carries 2 scores. (6 X 2 =
12)
1. (i). Which one is not considered as a green housegas
( Water vapour, Ozone, Carbon monoxide, Methane, Carbon dioxide)
(ii). What is meant by green houseeffect. [2]
Ans (i). Carbon monoxide
(ii). Earth’s atmosphere traps the heat from the sun and thus increasing the temperature of
earth’s surface.
2. .Write the difference between inter molecular and intra molecular Hydrogen bond. [2]
Ans Inter molecular Hydrogen bonding take place in between two different molecules of same
different compounds.
Intramolecular hydrogen bonding take place between hydrogen and an electro negative
element.with in a molecule.
3. Draw Sawhorse projection formula for staggered and eclipsed conformations
of ethane.
[2]
Ans H H H H H
H H H H H H H
Eclipsed conformation Staggered confirmation
4. . a) Name the test to detect the presence of Nitrogen in an organic compound . [1]
b) What is homologous series?
[1]
Ans a) Lassiagnes' test
b) A series of organic compounds which can be represented by a general formula and
successive/
adjacent members differ by a -CH2- group is called homologous series.
5. . Suggest a method to convert ethyne to benzene . [2]
Downloaded from www.hssreporter.com
, Ans Ethyne on passing through red hot iron tube, aromatisation take place to form Benzene.
6. State whether the following statements are true or false. [2]
(i) Sodium carbonate is commonly known as baking soda.
(ii) Group I elements are called alkali metals.
(iii) Sodium bicarbonate is a mild antiseptic for skin infections.
(iv) Except lithium chloride, other alkali metal chlorides form hydrates.
Ans (i). False (ii). True (iii). True (iv). False
7. (i). Important oxides of carbon are carbon monoxide and carbon dioxide.
Why carbon monoxide is considered as a poisonous gas?. [1]
(ii). Write the general formula of silicones. [1]
Ans (i).Carbon monoxide combines with haemoglobin of blood to form carboxy haemoglobin.
It destroys the oxygen carrying capacity of haemoglobin.
(ii). (R2SiO)n
8. State Hess’s law of constant heat summation. [2]
Ans Hess’s law states that whether a reaction is carried out in one step or several steps
total enthalpy change will be same
9.Calculate pH of 0.01M HCl.
[2]
pH = - log [ H+]
= - log 10-2
= 2
10. a) Name any one salt responsible for permanent hardness of water. [1]
b) Suggest one method to remove permanent hardness. [1]
Ansa] CaCl2 / CaSO4 /MgCl2 /MgSO4
b] Using washing soda/Calgon method/zeolite method/synthetic method.
11. Electron gain enthalpy of chlorine is greater than that of fluorine. why? [2]
Ans Due to small size, there is severe inter electronic repulsion in Fluorine.
12. Write the numerical values of universal gas constant (R in J/K mol ,L atm/ K mol
and L bar /K mol [2]
Ans R = 8.314 JK-1mol-1
R = 0.0821 L atmK-1mol-1
R = 0.083 L bar K-1mol-1 (any two)
Answer any 8 questions from 13 to 28 Each carries 3 scores (3x8=24)
Downloaded from www.hssreporter.com
CHEMISTRY TEACHERS ASSOCIATION
OXY CHEMISTRY 3.0
FIRST YEAR MODEL EXAMINATION 3.4 BASED ON FOCUS AREA 2021
ANSWER KEY
Time 2 hrs Cool Off Time : 20 minutes ( Maximum score 60 )
Answer any 6 questions from 1 to 12. Each carries 2 scores. (6 X 2 =
12)
1. (i). Which one is not considered as a green housegas
( Water vapour, Ozone, Carbon monoxide, Methane, Carbon dioxide)
(ii). What is meant by green houseeffect. [2]
Ans (i). Carbon monoxide
(ii). Earth’s atmosphere traps the heat from the sun and thus increasing the temperature of
earth’s surface.
2. .Write the difference between inter molecular and intra molecular Hydrogen bond. [2]
Ans Inter molecular Hydrogen bonding take place in between two different molecules of same
different compounds.
Intramolecular hydrogen bonding take place between hydrogen and an electro negative
element.with in a molecule.
3. Draw Sawhorse projection formula for staggered and eclipsed conformations
of ethane.
[2]
Ans H H H H H
H H H H H H H
Eclipsed conformation Staggered confirmation
4. . a) Name the test to detect the presence of Nitrogen in an organic compound . [1]
b) What is homologous series?
[1]
Ans a) Lassiagnes' test
b) A series of organic compounds which can be represented by a general formula and
successive/
adjacent members differ by a -CH2- group is called homologous series.
5. . Suggest a method to convert ethyne to benzene . [2]
Downloaded from www.hssreporter.com
, Ans Ethyne on passing through red hot iron tube, aromatisation take place to form Benzene.
6. State whether the following statements are true or false. [2]
(i) Sodium carbonate is commonly known as baking soda.
(ii) Group I elements are called alkali metals.
(iii) Sodium bicarbonate is a mild antiseptic for skin infections.
(iv) Except lithium chloride, other alkali metal chlorides form hydrates.
Ans (i). False (ii). True (iii). True (iv). False
7. (i). Important oxides of carbon are carbon monoxide and carbon dioxide.
Why carbon monoxide is considered as a poisonous gas?. [1]
(ii). Write the general formula of silicones. [1]
Ans (i).Carbon monoxide combines with haemoglobin of blood to form carboxy haemoglobin.
It destroys the oxygen carrying capacity of haemoglobin.
(ii). (R2SiO)n
8. State Hess’s law of constant heat summation. [2]
Ans Hess’s law states that whether a reaction is carried out in one step or several steps
total enthalpy change will be same
9.Calculate pH of 0.01M HCl.
[2]
pH = - log [ H+]
= - log 10-2
= 2
10. a) Name any one salt responsible for permanent hardness of water. [1]
b) Suggest one method to remove permanent hardness. [1]
Ansa] CaCl2 / CaSO4 /MgCl2 /MgSO4
b] Using washing soda/Calgon method/zeolite method/synthetic method.
11. Electron gain enthalpy of chlorine is greater than that of fluorine. why? [2]
Ans Due to small size, there is severe inter electronic repulsion in Fluorine.
12. Write the numerical values of universal gas constant (R in J/K mol ,L atm/ K mol
and L bar /K mol [2]
Ans R = 8.314 JK-1mol-1
R = 0.0821 L atmK-1mol-1
R = 0.083 L bar K-1mol-1 (any two)
Answer any 8 questions from 13 to 28 Each carries 3 scores (3x8=24)
Downloaded from www.hssreporter.com
