Your Progress — Chapter 8: Periodic Classification of Elements
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MCQI. Multiple Choice Questions1 mark each
Q.1 The number of periods and groups in the periodic table are______.
✓ Answer: (A)
Q.2 The basis of modern periodic law is______.
✓ Answer: (A)
Q.3 _____ group contains the member of halogen family.
✓ Answer: (A)
Q.4 _____ is a relative periodic property
✓ Answer: (A)
Q.5 Chemical formula of rust is ________.
✓ Answer: (A)
Q.6 In the alumino thermic process the role of Al is _____.
✓ Answer: (A)
Q.7 The process of coating the surface of metal with a thin layer of zinc is called______.
✓ Answer: (A)
Q.8 Which of the following have inert gases 2 electrons in the outermost shell.
✓ Answer: (A)
Q.9 Neon shows zero electron affinity due to _____.
✓ Answer: (A)
Q.10 ______ is an important metal to form amalgam.
✓ Answer: (A)
FillII. Fill in the Blanks1 mark each
| # | Statement (Answer in bold) |
|---|---|
| 1 | If the electronegativity difference between two bonded atoms in a molecule is greater than 1.7, the nature of bonding is ionic |
| 2 | 6th is the longest period in the periodical table. |
| 3 | Atomic number forms the basis of modern periodic table. |
| 4 | If the distance between two Cl atoms in Cl2 molecule is 1.98Å, then the radius of Cl atom is 0.99 A. |
| 5 | Among the given species A-,A+, and A, the smallest one in size is A+. |
| 6 | The scientist who propounded the modern periodic law is Henry Moseley. |
| 7 | Across the period, ionic radii decreases (increases,decreases). |
| 8 | Lanthanides and Actinides are called inner transition elements. |
| 9 | The chief ore of Aluminium is Bauxite. |
| 10 | The chemical name of rust is hydrated ferric oxide. |
MatchIII. Match the Following1 mark each
| Column A | Column B |
|---|---|
| Dental filling : silver | tin amalgam |
T/FIV. True or False1 mark each
| # | Statement | Answer | Correction (if False) |
|---|---|---|---|
| 1 | Moseley’s periodic table is based on atomic mass. | False | Moseley's periodic table is based on atomic number. |
| 2 | Ionic radius increases across the period from left to right. | False | Ionic radius decreases across the period from left to right. |
| 3 | All ores are minerals; but all minerals cannot be called as ores; | True | — |
| 4 | Al wires are used as electric cables due to their silvery white colour. | False | A1 wires are used in electric cables as they are good condutors. |
| 5 | An alloy is a heterogenous mixture of metals. | False | An alloy is a homogeneous mixture of metals. |
A&RV. Assertion & Reasoning2 marks each
Q.1
Assertion : The nature of bond in HF molecule is ionic
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✓ Answer
Reason : The electronegativity difference between H and F is 1.9
Answer: i. A and R are correct, R explains the A.
Answer: i. A and R are correct, R explains the A.
Q.2
Assertion : Magnesium is used to protect steel from rusting
▾
✓ Answer
Reason : Magnesium is more reactive than iron
Answer: iii. A is wrong, R is correct.
Answer: iii. A is wrong, R is correct.
Q.3
Assertion : An uncleaned copper vessel is covered with greenish layer.
▾
✓ Answer
Reason : copper is not attacked by alkali
Answer: i. A and R are correct, R explains the A.
Answer: i. A and R are correct, R explains the A.
ShortVI. Short Answer Questions2 marks each
Q.1
A is a reddish brown metal, which combines with O2 at < 1370 K gives B, a black coloured compound. At a temperature > 1370 K, A gives C which is red in colour. Find A,B and C with reaction.
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✓ Answer
Reddish brown metal A is copper.
Q.2
A is a silvery white metal. A combines with O2 to form B at 800oC, the alloy of A is used in making the aircraft. Find A and B
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✓ Answer
Silvery white metal is aluminium.
Q.3
What is rust? Give the equation for formation of rust.
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✓ Answer
When iron is exposed to moist air, it forms a layer of brown hydrated ferric oxide on its surface. This compound is known as rust and the phenomenon of formation of rust is known as rusting.
4Fe + 3O2 + x H20 \rightarrow 2Fe2O3.xH2O(rust)
4Fe + 3O2 + x H20 \rightarrow 2Fe2O3.xH2O(rust)
Q.4
State two conditions necessary for rusting of iron.
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✓ Answer
Two conditions necessary for rusting iron are (i) Oxygen (ii) Water.
NumericalVII. Numerical Problems3 marks each
Q.1
a) State the reason for addition of caustic alkali to bauxite ore during purification of bauxite. b) Along with cryolite and alumina, another substance is added to the electrolyte mixture. Name the substance and give one reason for the addition.
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✓ Answer
a) Caustic soda solution at 150^\circ is added to bauxite ore to obtain Sodium Meta Aluminate.
b) Fluorspar is added to the electrolyte mixture so as to lower the fusion temperature of the electrolyte.
b) Fluorspar is added to the electrolyte mixture so as to lower the fusion temperature of the electrolyte.
Q.2
The electronic configuration of metal A is 2,8,18,1.
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✓ Answer
The metal A when exposed to air and moisture forms B a green layered compound. A with con. H2SO4 forms C and D along with water. D is a gaseous compound. Find A,B,C and D.
Metal A is copper
2Cu + O2 + CO2 + H2O \rightarrow CuCO3.Cu(OH)2
2Cu [A:Copper] + O2 + CO2 + H2O \rightarrow CuCO3.Cu(OH)2 [B:Basic copper carbonate]
Cu + 2H2SO4 \rightarrow CuSO4 + SO2 ↑ + H2O
Cu [A:Copper] + 2H2SO4 \rightarrow CuSO4 [C:Copper sulphate] + SO2 ↑ [D:Sulphur-di-oxide] + H2O
[A: Cu : Copper]
[B: CuCO3.Cu(OH)2 : Basic copper carbonate]
[C: CuSO4 : Copper sulphate]
[D: SO2 : Sulphur-di-oxide]
Metal A is copper
2Cu + O2 + CO2 + H2O \rightarrow CuCO3.Cu(OH)2
2Cu [A:Copper] + O2 + CO2 + H2O \rightarrow CuCO3.Cu(OH)2 [B:Basic copper carbonate]
Cu + 2H2SO4 \rightarrow CuSO4 + SO2 ↑ + H2O
Cu [A:Copper] + 2H2SO4 \rightarrow CuSO4 [C:Copper sulphate] + SO2 ↑ [D:Sulphur-di-oxide] + H2O
[A: Cu : Copper]
[B: CuCO3.Cu(OH)2 : Basic copper carbonate]
[C: CuSO4 : Copper sulphate]
[D: SO2 : Sulphur-di-oxide]
Q.3
Explain smelting process.
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✓ Answer
Smelting: Smelting is the process of reducing the roasted metallic oxide from the metal in its molten condition. In this process, impurities are removed as slag by the addition of flux.
HOTIX. Higher Order Thinking3 marks each
Q.1
Metal A belongs to period 3 and group 13. A in red hot condition reacts with steam to form B. A with strong alkali forms C. Find A,B and C with reactions
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✓ Answer
Metal A is Aluminium.
2Al + 3H2O \rightarrow A12O3 + 3H2
2Al [(A) Aluminium] + 3H2O \rightarrow A12O3 [(B) Aluminium oxide] + 3H2
2A1 +2NaOH + 2H2O-- >2NaAlO2+3H2 ↑
2A1 +2NaOH + 2H2O-- >2NaAlO2 [C: Sodium meta aluminate] +3H2 ↑
(A) : Al : Aluminium
(B) : A12O3 : Aluminium oxide
(C) : 2NaAlO2 : Sodium meta aluminate
2Al + 3H2O \rightarrow A12O3 + 3H2
2Al [(A) Aluminium] + 3H2O \rightarrow A12O3 [(B) Aluminium oxide] + 3H2
2A1 +2NaOH + 2H2O-- >2NaAlO2+3H2 ↑
2A1 +2NaOH + 2H2O-- >2NaAlO2 [C: Sodium meta aluminate] +3H2 ↑
(A) : Al : Aluminium
(B) : A12O3 : Aluminium oxide
(C) : 2NaAlO2 : Sodium meta aluminate
Q.2
Name the acid that renders aluminium passive. Why?
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✓ Answer
Dilute or concentrated nitric acid does not attack aluminium, but it renders aluminium passive due to the formation of an oxide film on its surface.
Q.3
a) Identify the bond between H and F in HF molecule.
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✓ Answer
b) What property forms the basis of identification?
c) How does the property vary in periods and in groups?
a) Ionic bond
b) Electronegativity
c) Along the period, from left to right in the periodic table, the electronegativity increases. On moving down a group, the electronegativity of the elements decreases.
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c) How does the property vary in periods and in groups?
a) Ionic bond
b) Electronegativity
c) Along the period, from left to right in the periodic table, the electronegativity increases. On moving down a group, the electronegativity of the elements decreases.
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