Class 10
𝟏
Punakha Higher Secondary School Writing time 1𝟐 𝒉𝒓𝒔
Trial Run October 2014
(Paper 2 Chemistry)
Total Marks 80
------------------------------------------------------------------------------------------------------------------------------------------
READ THE FOLLOWING DIRECTIONS CAREFULLY:
1. A list of Atomic Weights of some elements for solving numerical problems is given at the end of the
question booklet.
2. In this paper, there are two sections: A and B. Section A is compulsory. You are expected to attempt
any four questions from Section B.
-----------------------------------------------------------------------------------------------------------------------------------------SECTION A (40 Marks)
Compulsory:
To be attempted by all candidates.
Question 1
(a)
Directions: Each question in this part is followed by four possible choices of answers.
Choose the correct answer and write it in your answer sheet
(i)
Metalloids in the periodic table belong to group
A IA
B
IIA
C
(ii)
(iii)
[15]
IIIA
D
IVA
Catalytic oxidation of ammonia in presence of spiral platinum at 800oC yields
A
N2O5
B
NO2
C
NO
D
N2
Which of the following components constitutes health salt?
A
NaHCO3
B
NaCl
C
KCl
D
Na2CO3
TRIAL RUN/CHEM 10/2014/PHSS/RD/BR
Page 1
(iv)
A metal ‘X’ can produce hydrogen on reacting with acid as well as alkali. Name the metal.
(v)
(viii)
(ix)
(x)
(xi)
copper
B
sodium
C
magnesium
D
zinc
The hydrocarbon when used with oxygen to produce high temperature flame for welding is
(vi)
(vii)
A
A
CH4
B
C2H2
C
C3H6
D
C4H10
When sugar is treated with conc. H2SO4, it turns into black mass. This is due to
A
dehydration
B
hydration
C
hydrolysis
D
decolourisation
Limestone (CaCO3) is added in the blast furnace during the extraction of iron to remove
A
CaO
B
CO
C
SO2
D
SiO2
The percentage composition of water in Na2CO3. 10 H2O comes out to be
A
60.50 B
62.93
C
75.23 D
80.33
The relative molecular mass of Ca3 (PO4)2 is
A
310
B
350
C
380
D
400
Electrolysis of molten lead bromide is carried out in
A
glass vessel
B
steel vessel
C
silica crucible
D
aluminium container
Which of the following is an alkaline earth metal?
A
lithium
B
Boron
C
potassium
D
Beryllium
TRIAL RUN/CHEM 10/2014/PHSS/RD/BR
Page 2
xii)
The formula of a compound formed between an element A (Atomic No 6) and element B
(Atomic No 17) will be
(xiii)
A
A2B2
B
AB4
C
A4B
D
AB
When a glass rod dipped in ammonia solution is brought at the mouth of jar containing
Hydrogen chloride, a dense white fumes forms, this is due to the formation of
(xiv)
(xv)
A
NH4Cl
B
NH4OH
C
NO2
D
HCl
Which one of the following will have maximum number of molecules at STP?
A
11 g carbon dioxide
B
8 g oxygen
C
7 g nitrogen
D
2 g of hydrogen
The empirical formula of a compound is CHO2. If the vapour density of the compound is 45, then
its molecular formula will be
A
C2H2O4
B
C2H2O2
C
C2H4O
D
CH2O
(b)
Fill in the blanks with appropriate words.
[6]
(i)
While moving from left to right in a given period, the number of shells ………. .
(ii)
A solution of a ………… electrolyte contains both ions and molecules of solute.
(iii)
Atomicity of ozone is …………. .
(iv)
A dirty green precipitate, insoluble in excess in excess NaOH and NH4OH solution indicates
the presence of …………. ion.
(v)
16 g of methane and 17 g of ammonia occupy ……….. ml.
(vi)
During the electroplating of an article using nickel, ………. solution is used as an electrolyte.
TRIAL RUN/CHEM 10/2014/PHSS/RD/BR
Page 3
(c)
Match each item in Column A with the most appropriate item in Column B. Rewrite the correct
matching pairs in your answer sheet.
Column A
(i) Butane
(ii) Vapour density
(iii) Duralumin
(iv) Galvanization
(v) Valence electrons
[5]
Column B
(a) air ships
(b) group number
(c) zinc
(d) isomerism
(e) 2 x atomic weight
(f) coins
(g )lead
(h) ½ x molecular weight
(d)
Explain the following statements.
(i)
Ionization potential increases across the period in the periodic table.
(ii)
During the extraction of aluminium by electrolysis, anode needs to be replaced periodically.
(iii)
Sulphuric acid is considered as ‘king of chemicals’.
(e)
Rewrite the following statements by changing only part(s) given in itlalics.
Rewrite the correct statements.
[6]
[5]
(i)
The precipitate formed on adding NaOH solution to AlCl3 is dull white in colour.
(ii)
Hoope’s cell is the device used for carrying out electrolysis of acidified water.
(iii)
When Cu turnings react with conc. HNO3, reddish brown gas N2O gets evolved.
(iv)
On reacting a mixture of ethane and oxygen in the ratio 9:1 in heated copper tube,
acetaldehyde is formed.
(v)
Concentrated HNO3 oxidizes sulphur to SO2.
(f)
Calcium hydroxide reacts with ammonium chloride to give ammonia according to the reaction
given below.
Ca(OH)2 + 2NH4Cl
CaCl2 + 2H2O + 2NH3
If 5.35 gms of ammonium chloride are used, calculate the weight of calcium chloride formed. [3]
TRIAL RUN/CHEM 10/2014/PHSS/RD/BR
Page 4
SECTION B (40 Marks)
Attempt any four questions
Question 2
(a)
A part of the periodic table is shown below. The letters represent the elements. Study the same
and answer the questions that follow.
Group/period IA
1
2
B
3
[4]
IIA
IIIA
IVA
VA
VIA
VIIA
C
I
D
E
F
H
G
J
0
A
(i)
Which element in the table has highest electro negativity?
(ii)
Which element forms an ion with single positive charge?
(iii)
What happens to the electron affinity on moving from left to right in the periodic table?
(iv)
Deduce the formula of the compound formed between element H and J in the table above.
(b)
Name the following.
(i)
A tribasic acid.
(ii)
The positive ion formed by acids when dissolved in water.
(iii)
The drying agent used to dry SO2 gas during its laboratory preparation.
(iv)
The ability of carbon atom to link with other carbon atoms forming ring and chain compounds.
(c)
Calculate the number of molecules in a drop of water weighing 0.05 gm.
[4]
[2]
Question 3
(a)
Complete the following equations and balance them.
i.
CH2= CH2 + Br2
ii.
KNO3
heat
iii. CuO + NH3
CCl4
[4]
..........
......... + ........
......... + ........ + ...........
iv. CuSO4 + NH4OH
TRIAL RUN/CHEM 10/2014/PHSS/RD/BR
......... + ...........
Page 5
(b)
Study the diagram given below and answer the questions that follow.
Gas A
dropper
water + phenolpthalein
(i)
What does the experiment given above demonstrate?
[1]
(ii)
What would be the colour of the fountain? Why?
[2]
(iii)
All apparatus used for preparing nitric acid in the laboratory should be made of glass.
Why ?
[1]
(c)
State two uses each of the following.
[2]
(i)
Stainless steel
(ii)
Nitric acid
Question 4
(a)
Give reasons for the following.
[5]
(i)
Atomic radius of elements increases moving down the group in the periodic table.
(ii)
Lime water turns milky on bubbling the gas, produced by reacting CaCO3 with dilute HCl.
(iii)
CaO is used as drying agent in lab preparation of ammonia and not H2SO4.
(iv)
64 g of SO2 and 44 g of CO2 contain the same number of molecules.
(v)
Noble gases are chemically inert.
(b)
Calcium carbide reacts with water to generate acetylene gas according to the equation given
below.
TRIAL RUN/CHEM 10/2014/PHSS/RD/BR
Page 6
Ca(OH)2 + C2H2
CaC2 + 2H2O
If 25.0 gms of CaC2 are used, calculate the:
(i)
Mass of water needed to react with CaC2,
(ii)
Volume of C2H2 liberated at the same time.
(c)
Draw the electron dot diagrams for the formation of the following compounds.
(i)
CaO
(ii)
[3]
[2]
NH4+
Question 5
(a)
A compound of sodium, sulphur and oxygen has the following percentage composition,
Na = 29.11%, S = 40.51% and O = 30.38%
(i)
Calculate the empirical formula of the compound.
[2]
(ii)
If the molecular mass of the compound is 158, determine its molecular formula.
[2]
(b)
Define the following.
[4]
(i)
Periodicity of elements
(ii)
electrometallurgy
(iii)
Electroneagativity
(iv)
homologous series
(c)
Compare the bleaching action of chlorine and sulphur dioxide.
[2]
Question 6
(a)
Give an example each for the following.
(i)
an acid salt
(ii)
a normal salt
(iii)
a liquid non metal
(iv)
a deliquescent substance
(b)
With regard to extraction of Aluminium by Baeyer’s process answer the
following questions.
(i)
Name an ore of Aluminium
(ii)
Outline the steps in conversion of this ore into pure Alumina. Write balanced chemical
[4]
[4]
equations.
(iii)
Mention any two uses of Aluminium.
TRIAL RUN/CHEM 10/2014/PHSS/RD/BR
Page 7
(iv)
(c)
Differentiate between metal and non metals based on the following properties.
[4]
i) physical state ii)
melting point iii)
conductivity
iv)
density.
What mass of NaOH would be required to produce 16.0 gms of antacid (Mg (OH) 2) by reacting
MgCl2 with NaOH?
MgCl2 + 2NaOH
Mg(OH)2 + 2NaCl
[2]
Question 7
(a)
A group of students decided to electroplate a car key using silver.
(i)
Draw a neat labeled diagram to represent the set up used for electroplating.
(ii)
What will be anode and cathode?
(iii)
Write the reaction at the anode and cathode.
(iv)
What happens to the size of the anode during the above process?
[4]
(b)
(i)
What is the purpose of Contact process?
[1]
(ii)
Which two gases combine during the contact process?
[1]
(iii)
Name the catalyst used in the process
[1]
(iv)
Mention two conditions required to increase the yield of the product in this process.
[1]
(c)
Write the molecular formula of the following compounds.
[2]
(i)
trichloro methane
ELEMENT
Na
C
O
Ca
P
N
Cl
H
Mg
S
(ii)
ethanol
ATOMIC WEIGHT
23
12
16
40
31
14
35.5
1
24
32
TRIAL RUN/CHEM 10/2014/PHSS/RD/BR
Page 8