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Class 10 Science Chapter 5 Periodic Classification of Elements
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Multiple Choice Questions
Q.1. In Mendeleev’s periodic table, gap was not left for one of the following elements. This element is :
( a ) Gallium.
( b ) Beryllium.
( c ) Germanium.
( d ) Scandium.
Ans :- ( b ) Beryllium.
Q.2. The Newlands law of octaves for the classification of elements was found to be applicable only up to the element :
( a ) Potassium.
( b ) Calcium.
( c ) Cobalt.
( d ) Phosphorus.
Ans :- ( b ) Calcium.
Q.3. According to Mendeleev’s periodic law , the elements were arranged in the periodic table in the order of
( a ) Decreasing atomic numbers.
( b ) Increasing atomic numbers.
( c ) Decreasing atomic masses.
( d ) Increasing atomic masses .
Ans :- ( d ) Increasing atomic masses.
Q.4. The three elements having chemical symbols of Si , B and Ge are :
( a ) Al metals.
( b ) All non – metals.
( c ) All metalloids.
( d ) Si is metalloids , B is metal and Ge is non – metal .
Ans :- ( c ) All metalloids .
Q.5. In Mendeleev’s periodic table , gaps were left for the elements to be discovered later on . An element which found a vacant place in the periodic table later on is :
( a ) Be
( b ) Si
( c ) Ge
( d ) Se
Ans :- ( c ) Ge.
Q.6. The three imaginary elements X , Y and Z represent a Dobernener’s triad . If the atomic mass of element X is 14 and that of element Y is 46 , then the atomic mass of element Z will be
( a ) 28
( b ) 60
( c ) 78
( d ) 72
Ans :- ( C ) 78
Q.7. The atomic numbers of four elements ? P , Q , R and S are 6 , 8 , 14 and 16 respectively . Our of these , the element known as metalloid is :
( a ) P
( b ) Q
( c ) R
( d ) S
Ans :- ( c ) R
Q.8. Which of the following statement is correct in regard to Sign the classification of elements ?
( a ) Elements in modern periodic table are arranged on the basis of increasing atomic masses .
( b ) Elements in Mendeleev’s periodic table are arranged on the basis of increasing atomic numbers .
( c ) In modern periodic table , the element nickel of lower atomic mass is kept before the element cobalt of higher atomic mass.
( d ) In modern periodic table , the isotopes of chlorine having different atomic masses are kept in the seme group .
Ans :- ( d ) In modern periodic table , the isotopes of chlorine having different atomic masses are kept in the seme group .
Q.9. Which of the following statement about the modern periodic table is correct ?
( a ) It has 18 horizontal rows known as periods.
( b ) It has 7 vertical columns known as periods.
( c ) It has 18 vertical columns known as groups .
( d ) It has 7 horizontal rows known as groups .
Ans :- ( c ) It has 18 vertical columns known as groups .
Q.10. An element X forms an oxide X₂O₃. In which Mendeleev’s periodic table is this element placed ?
( a ) Group II
( b ) Group III
( c ) Group V
( d ) Group VIII
Ans :- ( b ) Group III
Q.11. The modern periodic table was prepared by :
( a ) Dobereiner.
( b ) Newlands.
( c ) Bohr
( d ) Mendeleev.
Ans :- ( c ) Bohr.
Q.12. The atomic particle whose number in the atoms of an element always remains the same and which forms the real basis for the modern classification of elements is :
( a ) Electron.
( b ) Proton.
( c ) Neuton.
( d ) Meson.
Ans :- ( b ) Proton.
Q.13. Which of the following statements is not a correct statements about the trends when going from left to right across the periods of the periodic table ?
( a ) The elements become less metallic in nature .
( b ) The number of valence electrons increases .
( c ) The atoms loss their electrons more easily .
( d ) The oxides become more acidic.
Ans :- ( c ) The atoms loss their electrons more easily .
Q.14. The electronic configuration of the atom of an element X is 2 , 8 , 4. In modern periodic table , the element X is placed in :
( a ) 2nd group.
( b ) 4th group.
( c ) 14th group.
( d ) 8th group.
Ans :- ( c ) 14th group.
Q.15. The atomic number of an element is 20. In modern periodic table , this element is placed in :
( a ) 2nd period.
( b ) 4th period.
( c ) 3rd period.
( d ) 1st period.
Ans :- ( b ) 4th period.
Q.16. Five elements A , B , C , D and E have atomic numbers of 2 , 3 , 7 , 10 and 18 respectively . The elements which belong to the same period of the periodic table are :
( a ) A , B , C
( b ) B, C, D
( c ) A, D, E
( d ) B, D, E
Ans :- ( b ) B, C, D
Q.17. The elements A , B , C , D and E have atomic number 9 , 11 , 17 , 12 and 13 respectively . The pair of elements which belongs to the same group of the periodic table is :
( a ) A and B
( b ) B and D
( c ) A and C
( d ) D and E
Ans :- ( c ) A and C
Q.18. Which of the following element would lose an electron easily ?
( a ) Mg
( b ) Na
( c ) K
( d ) Ca
Ans :- ( c ) K
Q.19. Which of the following element does not lose an electron easily ?
( a ) Na
( b ) F
( c ) Mg
( d ) A1
Ans :- ( b ) F
Q.20. Where would you locate the element with electronic configuration 2 , 8 in the modern periodic table ?
( a ) Group 8
( b ) Group 2
( c ) Group 18
( d ) Group 10
Ans :- ( c ) Group 18
Q.21. An element which is an essential constituent of all organic compounds belongs to following group of modern periodic table :
( a ) Group 4
( b ) Group 14
( c ) Group 15
( d ) Group 16
Ans :- ( b ) Group 14
Q.22. Which of the following is the valence shell for the elements of second period of the modern periodic table?
( a ) M shell.
( b ) k shell.
( c ) L shell.
( d ) N shell.
Ans :- ( c ) L shell.
Q.23. The element which has the maximum number of valence electrons is :
( a ) Na
( b ) P
( c ) Si
( d ) AI
Ans :- ( b ) P
Q.24. The correct increasing order of the atomic radii of the elements oxygen , fluorine and nitrogen is :
( a ) O , F , N
( b ) N , F , O
( c ) O , N , F
( d ) F , O , N
Ans :- ( d ) F , O , N.
Q.25. The atomic numbers of the elements Na , Mg , K and Ca are 11 , 12 , 19 and 20 respectively . The element having the largest atomic radius is :
( a ) Mg
( b ) Na
( c ) K
( d ) Ca
Ans :- ( c ) K
Q.26. Which of the following are the correct characteristics of isotopes of an element ?
( i ) same atomic mass.
( ii ) same atomic number.
( iii ) same physical properties.
( iv ) same chemical properties.
( a ) ( i ) , ( ii ) and ( iv )
( b ) ( ii ) , ( iii ) and ( iv )
( c ) ( ii ) and ( iii )
( d ) ( ii ) and ( iv )
Ans :- ( d ) ( ii ) and ( iv )
Q.27. The correct formula of the oxide of Eka – aluminium element predicted by Mendeleev was :
( a ) EaO₃
( b ) Ea₃O₂
( c ) Ea₂O₃
( d ) EaO
Ans :- ( c ) Ea₂O₃
Q.28. The element which can form an acidic oxide should be on the one whose atomic number is :
( a ) 6
( b ) 16
( c ) 12
( d ) 19
Ans :- ( b ) 16
Q.29. The element which forms a basic oxide has the atomic number of :
( a ) 18
( b ) 17
( c ) 14
( d ) 19
Ans :- ( d ) 19
Q.30. Which one of the following does not increase while oily lo moving doesn the group of the periodic table ?
( a ) Atomic radius.
( b ) Metallic character.
( c ) Valence electrons.
( d ) Shells in the atoms.
Ans :- ( c ) Valency electrons .
Q.31. On moving from left to right in a period of the periodic A table , the atomic number of elements increases . What happens to the size of atoms of elements on moving from left to right in a period ?
( a ) Increases.
( b ) Decreases.
( c ) Remains he same.
( d ) First increases then decreases.
Ans :- ( b ) Decreases.
Q.32. Which of the following set of elements is written correctly in the order of their increasing metallic character ?
( a ) Mg , Al , Si
( b ) C , O , N
( c ) Na , Li , K
( d ) Be , Mg , Ca
Ans :- ( d ) Be , Mg , Ca.
Short Questions
Q.1. Write two merits of the modern periodic table .
Ans :- ( i ) The modern periodic table is based on the atomic numbers of elements which is the most fundamental property of elements .
( ii ) The modern periodic table helps us understand why elements in a group show similar properties but elements in different groups show different properties.
Q.2. Write the three similar chemical properties of lithium , sodium and potassium .
Ans :- ( i ) All these elements are metals .
( ii ) All of them react with water to form alkalis and hydrogen gas.
( iii ) All of them have a valency of 1.
Q.3. Write newlands law of octaves .
Ans :- When elements are arranged in the order of increasing atomic masses , the properties of the eight element starting from a given element are a repetition of the properties of the first element .
Q.4. Write three merits of Mendeleev’s classification of elements .
Ans :- ( i ) Mendeleev’s periodic law predicted the existence of some elements that had not been discovered at that time .
( ii ) Mendeleev’s periodic table could predict the properties of several elements on the basis of their positions in the periodic table .
( iii ) Mendeleev’s periodic table could accommodate noble gases when they were discovered .
Q.5. Write the two limitations of mendeleev’s classification of elements .
Ans :- ( i ) The position of isotopes could not be explained .
( ii ) Wrong order of atomic masses of some elements could not be explained .
Q.6. Why all the elements of a group show similar chemical properties ?
Ans :- All the elements of a group in the periodic table have similar electronic configurations that is having the same number of valence electrons , so all the elements of a group show similar chemical properties .
Q.7. Write two advantages of the periodic table .
Ans :- ( i ) The periodic table has made the study of chemistry systematic and easy . It acts as an aid to memory.
( ii ) It is easier to remember the properties of an element if its position in the periodic table is known .
Q.8. Which of the following belong to :
( i ) The same period.
( ii ) the same group ?
| Element | Atomic number |
| A | 2 |
| B | 10 |
| C | 5 |
Ans :- Electronic configuration of A =
Electronic configuration of B = 2 ,8
Electronic configuration of C = 2, 3
( i ) The elements B and C have the same valence shell(L) therefore B and C belong to the same period .
( ii ) Elements A and B belong to the same group because their valence shells are completed .
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