NCERT Class 11 Chemistry Chapter 3 Classification Of Elements And Periodicity In Properties Very Short Question And Answers

NCERT Solutions For Class 11 Chemistry Chapter 3 Classification Of Elements And Periodicity In Properties Very Short Question And Answers

Question 1. Who proposed the ‘law of octaves’?
Answer: Newland

Question 2. For which of the elements, the ‘Law of octave’ is not applicable?
Answer: Heavy mental

Question 3. Identify the element predicted by Mendeleev as ekaaluminium.
Answer: Gallium

Question 4. Mention the name of the group in the periodic table, which contains solid, liquid, and gaseous elements.
Answer: Group 72 or 17

Question 5. Mention the position of the alkali metals in the periodic table.
Answer: Group 1 A or 1

Question 6. Give an example of an element whose atomic mass has been corrected by Mendeleev’s periodic table.
Answer: Be

Question 7. Who proved that atomic number but not atomic mass is the more proper determining factor of the periodicity of elements?
Answer: Moseley

Question 8. Give an example of d -a block element which is not regarded as a transition element.
Answer: Zn

Question 9. How many rare earth elements are present in the periodic table? Give an example-
Answer: 14

Question 10. Give the common electronic configuration of d-block elements.
Answer: (n-1) s1-10 ns 1-2

Question 11. Name the transition element having the lowest atomic mass.
Answer: Se

Question 12. Which element gives brick red coloration to the flame? In which block, the element is in the periodic table?
Answer: Ca, s-block

Question 13. Mention the respective block of the elements having atomic numbers 7, 11, and 22.
Answer: p,s,d

Question 14. What do you mean by representative elements?
Answer: Elements Of S and P- block’s

Question 15. Give two terminal elements of the rare earth element series.
Answer: Ce, lu

Question 16. How will you detect the starting and ending of a period in the periodic table?
Answer: By electronic configuration.

Question 17. Which block contains inner transition elements?
Answer: F

Question 18. Give an example of a transition element, which has filled d-subshellinits ground state.
Answer: Cu

Question 19. Why the ions or atoms of the transition elements are paramagnetic?
Answer: Due to the presence of unpaired d -electrons, 20. Cations of group-1A and 2A,

Question 20. Give an example of a diamagnetic.
Answer: Cations of group-1A and 2A,

Question 21. Why and Co called ferromagnetic?
Answer: They can easily be converted into magnets.

Question 22. Which element gives golden-yellow coloration to the flame?
Answer: Na

Question 23. Why Mg cannot be identified by flame test?
Answer: They can easily be converted into magnets.

Question 24. Which are called ‘noble metals’?
Answer: Elements of 5d -series (especially Pt, Au, and Hg ),

Question 25. Give the electronic configuration of the outermost shell of lanthanides.
Answer: 4f^1-14 5d^0-16s²

Question 26. Which of the groups in the periodic table contain all the metallic elements?
Answer: Group-2A

Question 27. Give the names of the ‘noble gas’ elements present in the second and fifth periods.
Answer: Ne, Xe

Question 28. Mention the name and atomic number of the element present in group 13 of the third period.
Answer: Al.13

Question 29. Give the electronic configuration of the fifth element ofthe first transition series.
Answer: Electronic configuration of Mn

Question 30. Identify the transition element(s): K, Mn, Ca, Cs, Fe, Cu, pb.
Answer: Mn, Fe, Cu, Pb,

Question 31. Name two elements that do not give a flame test.
Answer: Be, Mg

Question 32. Which lanthanide elements have only 1 electron in a 5dsubshell?
Answer: Lu

Question 33. Write the outermost electronic configuration of chalcogens.
Answer: ns² np⁴

Question 34. What will be the position in the periodic table of the element having electronic configuration ls²2s²2p⁴?
Answer: Second period, Grop -16

Question 35. Mention the position of the pnictogens in the long form of the periodic table.
Answer: 15

Question 37. Which element has the highest oxidizing property?
Answer: Fluorine

Question 38. Give one example of each metal, nonmetal, or metalloid presenting the p-block of the periodic table.
Answer: Pb.N.As

Question 39. Give the names of two non-metals present in s -block of the periodic table.
Answer: H₂.He

Question 40. What is the unit of electron affinity?
Answer: Kj-mol^-1

Question 41. Is the value of the electron affinity of an element zero?
Answer: Yes

Question 42. Between Fe2+ and Fe3+, which is smaller in size, and 6. Why?
Answer: Fe³⁺, Z/e ratio is higher,

Question 43. Which element of each pair has higher electron affinity?

• Br, Cl
• F, Cl
• O, S

Answer:

• Cl
• Cl
• S

Question 44. The first ionization potential of carbon is 11.2 eV. State whether the value of the first ionization potential of silicon is the same or greater or less than that of carbon
Answer: Lower

Question 45. Arrange s,p,d & f-subshells according to the screening power.
Answer: S>p>d> f

Question 46. Which element has the lowest ionization potential?
Answer: Cs

Question 47. Which element has the highest ionization potential?
Answer: He

Question 48. What is the unit of ionization potential?
Answer: eV atom^-1

Question 49. What is the change observed in the covalent character of the oxides of the elements starting from Na to Cl in the third period?
Answer: Increases

Question 50. Arrange the following in increasing order of ionic radius: Na⁺, F^–, O^2-, Al³⁺, N^3-.
Answer: Al³⁺ < Na⁺ < F^– < O^2- < N^3-

Question 51. Why does nitrogen have a higher ionization enthalpy than that of Oxygen? Arrange the following in increasing order of acidity: NO₂, Al₂O₃, SiO₂, CIO₂
Answer: Na < Al< Mg < Si

Question 52. What will be the order of, Mg, Al, and SI in terms of the first ionization enthalpy?
Answer: Mg²⁺ < Na⁺ < F^– < O^2-

Question 53. Arrange the following ions in ascending order of radius: Na⁺, F^–, O^2-, Mg²⁺.
Answer: Mg²⁺ < Na+ <F^– < O^2-

Question 54. Arrange Mg, Al, Si, and Na in the increasing order of their ionization potentials.
Answer: Na < Al < Mg < Si

Question 55. How many periods and groups are there in the present form (i.e., long form) of the periodic table?
Answer: 7 periods and 18 groups

Question 56. Which group ofthe long form of the periodic table contains solid, liquid, and gaseous elements?
Answer: Group-17.

Question 57. Identify the following as acidic, basic, or amphoteric oxides: BeO, Al₂O₃
Answer:

Acidic oxide: SiO, basic Oxide: CaO, Amphoteric oxides: BeO, Al₂O₃.

Question 58. Between XaOH and CsOH, which one is more basic and why?
Answer:

CsOH is more basic than NaOH because the electronegativity of Cs is more electropositive than Na.

Question 59. Write down the names ofthe coinage metals and indicate their positions in the long form ofthe periodic table.
Answer: Cu, Ag, Au (periods 4, 5, & 6 in group 11).

Question 60. Indicate the period that contains the first series of transition elements.
Answer: 4th period.

Question 61. Which block in the periodic table contains metals, nonmetals, and metalloids? Give three examples of metalloids.
Answer: p -block; Si, Ge, As

Question 62. Write the IUPAC name and symbol of the element with atomic number 135.
Answer:

IUPAC name: Untripentium; Symbol: Utp

Question 63. Arrange the following elements in decreasing order of their atomic radius: Na, H, Si, S, P, Cl
Answer: Na > Si > P > S > Cl > H

Question 64. Indicate the largest and smallest species among the following: Mg, Al, Mg²⁺, Al³⁺⁺
Answer:

Largest: Mg

Smallest: Al³⁺

Question 65. Arrange the following compounds in increasing order of their reducing: NH₃, PH₃, and AsH₃
Answer: NH₃ < pH₂< AsH₃

Question 66. Classify as basic, amphoteric, or acidic: BeO, Al₂O₃, CaO, SiO₂
Answer:

BeO, Al₂O₃: Amphoteric

CaO: Basic

SiO₂: Acidic

Question 67. Write the names ofthe smallest cation and anion.
Answer: H⁺ and H^–

Question 68. Mention the names of two noble metals and indicate their positions in the periodic table.
Answer: Pt and Au. In the periodic table, they are present in the 6th period in the 10th and 11th groups respectively.

Question 69. Based on atomic number and position in the periodic table arrange the following elements in decreasing order of their metallic character: Si, Na, Mg, P, Be.
Answer: Na > Mg > Be > Si > P

Question 70. Arrange in increasing order of oxidizing power: F, Br, Cl, I
Answer: I < Br < Cl < F

Question 71. The atom of an element has the electronic configuration ls²2s²2p⁶3s²3p⁵. Identify a metal or non-metal.
Answer: Non-metal

Question 72. Which is most acidic: S₃, P₂O₅, ZnO, Na₂O?
Answer: SO₃ is the most acidic compound.

Question 73. Which is most basic: SiO₂, MgO, Al₂O₃, Na₂O?
Answer: Na₂O is the most basic compound

Question 74. For which elements, Newlands’ law of octaves is not applicable?
Answer: Heavier elements beyond Ca

Question 75. Which periods in Mendeleev’s periodic table (modified form) do not contain subgroups?
Answer: Periods 1, 2 and 3

Question 76. How many periods and groups are there in the present form (i.e., long form) of the periodic table?
Answer: 7 periods and 18 groups

Question 77. Write down the names ofthe coinage metals and indicate their positions in the long form ofthe periodic table.
Answer: Cu, Ag, Au (periods 4, 5, & 6in group 11).

Question 78. Mention the names of the first member of each of the first, second, and third series of transition elements.
Answer: Scandium (Sc), Yttrium (Y), and Lanthanum (La)

Question 79. Mention the names of the first and last members of the actinide series.
Answer: Thorium (Th) and Lawrencium (Lr).

Question 80. What are pnictogens and chalcogens?
Answer: Gr-15 elements: pnictogens; Gr-16 elements: chalcogens

Question 81. Elements of the same group exhibit similar chemical properties—why?
Answer: Because they have similar outer electronic configurations.

Question 82. Why are sodium (Na) and potassium (K) placed in the same group of the periodic table? Give any two reasons.
Answer: (n- l)d^1-10 ns¹,(n-2)f^1-14(n-l)d^0-1ns²

Question 83. Give general electronic configurations of 1 transition elements and 2 inner-transition elements
Answer: Due to the presence of unpaired electrons in (n-l)d subshell

Question 84. Which group ofthe long form of the periodic table contains solid, liquid, and gaseous elements?
Answer: Group-17.

Question 85. Find the atomic number of an element that belongs to the third period and group 17 in the periodic table.
Answer: The atomic number ofthe given element = 17

Question 86. An element belongs to the third period of p -block. It has five valence electrons. Predict its group.
Answer:

Group ofthe element= 10 + no. of valence electrons = 10 + 5 = 15

Question 87. What is the reason for the strong reducing character of s-block elements?
Answer: Since they have low ionization energy.

Question 88. Which one of the following exhibits paramagnetism? Sc³⁺+, Cr³⁺, Cu⁺, Zn².
Answer: Cr³⁺ : [Ar]3d³. Due to the presence of unpaired electrons, it exhibits paramagnetism.

Question 89. Name the elements with which even and odd series of 4th, 5th, and 6th periods begin.
Answer: Even series begins with K, Rb, and Cs. The odd series begins with Cu, Ag, and Au.

Question 90. How many periods and groups are there in the modem version of Mendeleev’s table?
Answer: There are 7 periods and 9 groups of a modern version of Mendeleev’s periodic table.

Question 91. Arrange the following elements in the increasing order of their first ionization enthalpy. Li, Be, Na, Mg
Answer: Na < Li < Mg < Be

Question 92. Arrange the following elements in the decreasing order of their electro-negativity. Si, N, F, Cl
Answer:  F >Cl > N> Si

Question 93. What are the various factors due to which the ionization enthalpy of the main group elements tends to decrease down a group?
Answer: The two factors are Atomic size and screening effect.

NCERT Solutions For Class 11 Chemistry Chapter 3 Classification Of Elements And Periodicity In Properties Fill In The Blanks

Question 1. Mendeleev’s periodic law was similar to the law proposed by the scientist______________.
Answer: Lothar Meyer

Question 2. In Mendeleev’s periodic table, the______________incomplete period.
Answer: Seventh

Question 3. The starting elements of even series are K, Rb, and ______________period is an
Answer: Cs

Question 4. The starting elements of odd series are______________Au.
Answer: CU

Question 5. Meneleev’s triad elements are Ag and are the ______________ fundamental property of the element.
Answer: Transition elements

Question 6. ‘The elements from 58Ce to 71Lu are called ______________
Answer: lanthanides

Question 7. Be, Mg, Ca are called______________1L
Answer: Alkaline Earth

Question 8. Cu, Ag, Au are called______________metals.
Answer: Coinage

Question 9. S, Se, Te are called ______________
Answer: Chalcogens,

Question 10. The potential of s -s-block elements is. Except Be and______________ the s -block elements response to the flame test.
Answer: Low

Question 11. Except Be and______________the s -block elements response to the flame test.
Answer: Mg

Question 12. The s -s-block elements of the fourth, fifth, and sixth periods can form complex compounds by vacant d -orbital. in as they have ______________.
Answer: Coordinate Covalency

Question 13. Noble metals are chemically______________.
Answer: Insert

Question 14. F-block elements are _ the presence of odd electrons. block elements generally form colored in nature due to the omplex compounds.
Answer: Paramagnetic

Question 15. Block elements Generally from colored complex compounds ______________.
Answer: d

Question 16. Zn, Cd, and are not they are d-block elements.
Answer: Hg

Question 17. The element with electronic configuration ls22s22p4 is presentin group______________.
Answer: 16

Question 18. The general electronic configuration of transition
elements is______________
Answer: (n-1)d^{1- 10}-10 ns^1-2

Question 19. Effective nuclear charge = total nuclear change ______________.
Answer: Screening Constant,

Question 20. The IUPAC name of the element having an atomic number 150 is______________
Answer: Unpentrilum

Question 21. For homonuclear diatomic molecule, covalent radius = ______________x intemuclear distance.
Answer: \(\frac{1}{2}\)

Question 22. The internuclear distance of the HCl molecule is 1.36 A and the covalent radius of the chlorine atom is 0.99 A. Thus, the covalent radius of the hydrogen atom will be______________.
Answer: 0.37

Question 23. The covalent radius of an element is ______________ der Waals radius.
Answer: Shorter

Question 24. Anionic radius is ______________ radius.
Answer: Greater

Question 25. On moving from left to right across a period, the acidic property of oxide of element______________.
Answer: Increases

Question 26. Hydrides of most of the non-metals are ______________nature.
Answer: Colvent and nonpolar

Question 27. The first ionization potential of carbon is. the second ionization potential is ______________.
Answer: Increases

Question 28. Among the halogens,______________ nature.
Answer: Idonine

Question 29. Electron affinity of Be and are ______________ almost same.
Answer: Mg

Question 30. In a particular energy Level(orbit), the Followers the orders s>p>f.
Answer: Screening effect,

Question 31. In the case of elements belonging to the same group, ionic radii with increases in atomic number ______________.
Answer: Increases

Question 32. F-,Ar,Mg²⁺,Rb⁺ are inons ______________
Answer: Isoelectronic

Question 33. The ionization enthalpy of Cu and K can be explained based on______________.
Answer: Screening effect

Question 34. of the atom of any element and the first ionization enthalpy of its anion (unit -ve charge) are the same.
Answer: Electron affinity

Question 35. Atomic mass = Atomic volume x______________.
Answer: Density

Question 36. Low solubility of Li₂CO₃ and MgCO₃ in water can be explained by______________.
Answer: Diagonal relationship.