Periodic Classification of Elements

Samacheer Book Back Questions And Answers For Science Standard 10 “Periodic Classification of Elements“

I. Choose the best answer:
1. The number of periods and groups in the periodic table are _____.
a) 6,16
b) 7,17
c) 8,18
d) 7,18

2. The basis of modern periodic law is _____.
a) atomic number
b) atomic mass
c) isotopic mass
d) number of neutrons

3. _____ group contains the member of halogen family.
a) 17th
b) 15th
c) 18th
d) 16th

4. _____ is a relative periodic property.
a) atomic radii
b) ionic radii
c) electron affinity
d) electronegativity

5. Chemical formula of rust is _____.
a) FeO.xH₂O
b) FeO₄.xH₂O
c) Fe₂O₃.xH₂O
d) FeO

6. In the alumino thermic process the role of Al is _____.
a) oxidizing agent
b) reducing agent
c) hydrogenating agent
d) sulphurising agent

7. The process of coating the surface of metal with a thin layer of zinc is called _____.
a) painting
b) thinning
c) galvanization
d) electroplating

8. Which of the following have inert gases 2 electrons in the outermost shell.
a) He
b) Ne
c) Ar
d) Kr

9. Neon shows zero electron affinity due to _____.
a) stable arrangement of neutrons
b) stable configuration of electrons
c) reduced size
d) increased density

10. _____ is an important metal to form amalgam.
a) Ag
b) Hg
c) Mg
d) Al

II. Fill in the blanks:
1. If the electronegativity difference between two bonded atoms in a molecule is greater than 1.7, the nature of bonding is _____.
2. _____ is the longest period in the periodical table.
3. _____ 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 _____.
5. Among the given species A^–,A⁺, and A, the smallest one in size is _____.
6. The scientist who propounded the modern periodic law is _____.
7. Across the period, ionic radii _____ (increases, decreases).
8. _____ and _____ are called inner transition elements.
9. The chief ore of Aluminium is _____.
10. The chemical name of rust is _____.

Answers:
1. ionic
2. 6th
3. Atomic number
4. 0.99 A
5. A⁺
6. Henry Moseley
7. decreases
8. Lanthanides and Actinides
9. Bauxite
10. hydrated ferric oxide

III. Match the following:
1. Galvanisation                    A. Noble gas elements
2. Calcination                        B. Coating with Zn
3. Redox reaction                  C. Silver-tin amalgam
4. Dental filling                      D. Alumino thermic process
5. Group 18 elements           E. Heating in the absence of air

Answers:
1. B
2. E
3. D
4. C
5. A

IV. True or False: (If false give the correct statement)
1. Moseley’s periodic table is based on atomic mass.
2. Ionic radius increases across the period from left to right.
3. All ores are minerals; but all minerals cannot be called as ores.
4. Al wires are used as electric cables due to their silvery white colour.
5. An alloy is a heterogenous mixture of metals.

Answers:
1. False (Moseley’s periodic table is based on atomic number)
2. False (Ionic radius decreases across the period from left to right)
3. True
4. False (Al wires are used in electric cables as they are good conductors)
5. False (An alloy is a homogeneous mixture of metals)

V. Assertion and Reason:
1. Assertion: The nature of bond in HF molecule is ionic
Reason: The electronegativity difference between H and F is 1.9
a. A and R are correct, R explains the A.
b. A is correct, R is wrong.
c. A is wrong, R is correct.
d. A and R are correct, R doesn’t explains A.

2. Assertion: Magnesium is used to protect steel from rusting
Reason: Magnesium is more reactive than iron
a. A and R are correct, R explains the A.
b. A is correct, R is wrong.
c. A is wrong, R is correct.
d. A and R are correct, R doesn’t explains A.

3. Assertion: An uncleaned copper vessel is covered with greenish layer.
Reason: copper is not attacked by alkali
a. A and R are correct, R explains the A.
b. A is correct, R is wrong.
c. A is wrong, R is correct.
d. A and R are correct, R doesn’t explains A.

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