Objective questions
Objective questions
1) Which one of the following was the earliest attempt of classification of elements?
- (a) Classification of elements into metals and non-metals
- (b) Newlands’ Law of Octaves.
- (c) Dobereiner’s Triads
- (d) Mendeleef’s Periodic Table.
Ans: – Option (d).
2) The ‘law of octaves’ was given by
- (a) Mendeleev
- (b) Newlands
- (c) Lother Meyer
- (d) Dobereiner.
Ans: – option (b).
3) According to the periodic law given by Mendeleev, the properties of anelement are a periodic function of its
- (i) atomic volume
- (ii) atomic size
- (iii) atomic number
- (iv) atomic mass.
Ans: – Option (iv).
4) The particle which is universally present in the nuclei of all elements is
- (a) neutron
- (b) proton
- (c) electron
- (d) α-particle.
Ans: – Option (b).
5) Potassium is more metallic than sodium because
- (a) both have 1 electron in their outermost shell.
- (b) both are highly electropositive.
- (c) sodium is larger in size than potassium.
- (d) potassium is larger in size than sodium.
Ans: – Option (c).
7) Which one of the following elements in its chloride does not show the valenceequal to its valence electrons ?
- (a) NaCl
- (b) MgCl2
- (c) AlCl3
- (d) PCl3.
Ans: – Option (d).
8) Which one of the following elements has the least tendency to form cation?
- (a) Na
- (b) Ca
- (c) B
- (d) Al.
Ans: – Option (c).
9)Which one of the following does not belong to the family of the alkali metals?
- (a) Li
- (b) Na
- (c) Be
- (d) K.
Ans: – Option(c).
10) The number of elements in the 5th period of the periodic table is
- (a) 2
- (b) 8
- (c) 32
- (d) 18.
Ans: – Option (c).
11) The elements with atomic number 9 resembles with the element having atomic number
- (a) 35
- (b) 27
- (c) 17
- (d) 8.
Ans: – Option (c).
12) In which period of the periodic table, an element with atomic number 20 is placed?
(a) 4
(b) 3
(c) 2
(d) 1.
Ans: – Option (a).
Mark the following statements True (T) or False (F) :
1) The properties of the middle element in a Dobereiner’s triads are intermediate between those of the other two. (True)
2) The vertical columns in the periodic table are called periods. (False)
3) Mendeleev depended only on the atomic mass of elements for his classification. (True)
4) All elements present in a group are chemically similar. (True)
5) The modern periodic law is based upon atomic mass. (False)
6) The importance of atomic number as the fundamental property was realized by Henry Mosely. (True)
7) There are 18 groups in the modern periodic table. (True)
8) Non-metals are present in the middle portion of the periodic table. (True)
9) Each period in modern periodic classification begins with filling of electrons in a new shell. (True).
III. Fill in the blanks:
1. According to the modern periodic law, the properties of elements are periodicfunction of their ……… atomic number…………
2. The ……. group………….. number is same as the number of shells which in gradually filled up in the elements of this period.
3. In normal elements of a particular period the electrons are gradually filled in……..lower…………. shell.
4. All elements of a particular group have ……..same…………. electronic configurations.
5. In the modern periodic table, groups are numbered from ………1………… to…….18…………..
6. The second and third periods of the periodic table are called ……..short………….periods.
7. The main group elements are present in group 1 and 2 on the left side and………17………… to …..18……………. on the right side of the periodic table.
8. All the group eighteen elements (except the first one) contain ……..0………….valence electrons.
9. All transition elements are metals with ……..high…………. melting and boiling points.
10. The group of 14 rare-earth elements belonging to the group 3 and 7th periodare called …………………
11. All elements present in a given ……… group………… have the same valency.
12. Atomic size ……… decrease………… in a period from left to right.
13. Magnesium is ……..less…………. metallic than calcium.
14. Carbon belongs to group ………14……….. of the Periodic table.
15. All the elements of group 15 have ….3…………….. valence electrons.
B. Subjective Questions
I. Very short Answer Questions (Answer in one word or one sentence).
1)What was the earliest classification of elements?
Ans: – The earliest classification of elements is according to their atomic masses.
2) State Newlands’ law of octaves.
Ans: – The Newland law states the eight elements subsequently shows same property.
3) Which classification of elements failed after the discovery of noble gases ?
Ans: – Mendeleev classification failed after the discovery of noble gases.
4) State Mendeleev’s Periodic Law.
Ans: – Mendeleev period law states that the elements are kept in the periodic table according to their atomic masses.
5) How were the groups numbered in the Mendeleev’s periodic table?
Ans: – There are 8 group in Mendeleev periodic table.
6) Name the fundamental properties of element on which the modern periodic law is based.
Ans: – Atomic number.
7) How many groups are there in the modern periodic table?
Ans: – There are 18 group in modern periodic table.
8) How have groups been numbered in the modern periodic table?
Ans: – 18 group been number in modern periodic table.
9) What are normal elements ?
Ans: – In group 1, 2 and from 13 to 17 are normal element.
10) What are the elements present in the middle portion of the modern periodic table called?
Ans: – Transitions elements.
11)What is atomic size?
Ans: – The size of elements including its shell.
12) How does atomic size vary in a period and in a group?
Ans: – Atomic size increasing down a group and decrease from left to right a period.
13) Where would the element with largest atomic size be placed in any group?
Ans: – At the lowest point under a group.
14) Give the number of a group in which metallic, metalloid and non-metallic, all three types of elements, are present.
Ans: – Group 14.
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