Periodic Classification of Elements
Periodic Classification of Elements
Multiple Choice Questions
Que 1. The valence shell electronic configuration of transition elements is
(1) ns1 (2) ns2np5 (3) ns 1–2 (n – 1) d1–10 (4) ns2 (n – 1)d10
Ans 1. (3) ns 1–2 (n – 1) d1–10
Que 2. Eka-aluminium and Eka-silicon are known as
(1) Gallium and Germanium (2) Aluminium and Silicon
(3) Iron and Sulphur (4) Boron and Technitium
Ans 2. (1) Gallium and Germanium
Reason: Eka is a Sanskrit word that means one.
Eka-aluminium is known as gallium and Eka-silicon is known as germanium because gallium is similar in properties to aluminium and one next to it and germanium is similar in properties to silicon and one next to it.
Que 3. Which is mismatched regarding the position of the element as given below?
(1) X (Z = 89) – f block, 6th period (2) Y (Z = 100) – f block, 7th period
(3) Z (Z = 115) – d block, 7th period (4) Both (1) & (3)
Ans 3. (3) Z (Z = 115) – d block, 7th period
Reason: Z = 115 belongs to p-block, 7th period.
Que 4. Modern periodic law is
(1) The physical and chemical properties of the elements are periodic functions of their atomic numbers
(2) The physical and chemical properties of the elements depend upon the energy of the electrons
(3) The physical and chemical properties of the elements depend upon atomic weight.
(4) None of these
Ans 4. (3)
Que 5. Which of the following statements about the modern periodic table is incorrect?
(1) The p-block has 6 columns because a maximum of 6 electrons can occupy all the orbitals in the p-subshell
(2) The d-block has 8 columns because a maximum of 8 electrons can occupy all the orbitals in the d-subshell
(3) Each block contains a number of columns equal to the number of electrons that can occupy the subshell
(4) The block indicates the value of the azimuthal quantum number for the last subshell which
received electrons
Ans 5. (2) The d-block has 8 columns because a maximum of 8 electrons can occupy all the orbitals in the d-subshell
Reason: The d-block has 10 columns because a maximum of 10 electrons can occupy all the orbitals in the d-subshell.
Periodic Classification of Elements
Que 6. Elements that generally exhibit multiple oxidation states and whose ions are usually coloured are
(1) Metalloids (2) Transition elements (3) Non-metals (4) Gases
Ans 6. (2) Transition elements
Que 6. IUPAC name of the element having atomic number 108 is
(1) Unniloctium (2) Ununoctium
(3) Nilniloctinium (4) Ununoctinium
Ans 7. (1) Unniloctium
Que 8. Which of the following is a representative element?
(1) Zn (2) Sr (3) Cu (4) Fe
Ans 8. (2) Sr
Reason: Any element of s and p – Block is called the representative Element.
Que 9. Which of the following is not correct for iso-electronic ions?
(1) They have the same number of electrons around their nuclei
(2) Higher the atomic number, higher will be positive charge in a series of isoelectronic ions of the same period
(3) Isoelectronic ions have the same electric charge
(4) An isoelectronic series may have both positively and negatively charged ions
Ans 9. (3)
Que 10. Which of the following oxide is expected to react readily with NaOH?
(1) Na₂O (2) CaO (3) NO (4) Cl₂O₇
Ans 10. (4) Cl₂O₇
Reason: When Cl₂O₇ is dipped into water, an acid forms which is known as perchloric acid.
When NaOH is dipped into water, it reacts with water to form NaO. Thus, this proves that Cl₂O₇ is acidic in nature and NaOH is basic in nature.
We know that substances that are acidic in nature react strongly with substances of basic nature. Thus, Cl₂O₇ reacts strongly with NaOH.
Periodic Classification of Elements
Que 11. When a neutral atom is converted into a cation its
(1) Atomic weight increases (2) Atomic weight decreases
(3) Size increases (4) Size decreases
Ans 11. (3) Size increases
Reason: When a neutral atom is converted into a cation more effective nuclear charge is experienced by electrons. Size is inversely proportional to the effective nuclear charge. Thus, the size of a cation is less than the a neutral atom.
Que 12. Of the following, which one is a correct statement?
(1) Ionic radius of metal is the same as its atomic radius
(2) The ionic radius of metal is greater than its atomic radius
(3) The atomic radius of a non-metal is more than its ionic radius
(4) The ionic radius of metal is less than its atomic radius
Ans 12. (4) The ionic radius of metal is less than its atomic radius
Reason: A metal after losing electrons becomes a cation and the size of the cation is always smaller than its parent atom.
Que 13. Which of the following N3–, O2–, F– is largest in size?
(1) N3– (2) O2– (3) F– (4) All of these
Ans 13. (1) N3–
Que 14. The radii of F, F–, O and O2– are in the order
(1) O2– > O > F– > F (2) F– > O2– > F > O
(3) O2– > F– > O > F (4) O2– > F– > F > O
Ans 14. (3) O2– > F– > O > F
Reason: The size of the anion is larger than its parent atom. Also, the more the effective nuclear charge, the lesser is the size. So, the correct order is: O2– > F– > O > F
Que 15. Which ion has the largest radius?
(1) Se2– (2) F– (3) O2– (4) Rb+
Ans 15. (4) Rb+
Reason: While moving from left to right in the periodic table the nuclear attraction between nucleus and electrons increases and the size decreases. While moving down the group as the number of shells increases the radius increases. Rb+ belongs to the first group and fall in the 5th period.
O2– and F– are placed in the second period of the periodic table.
Se2– belongs to the 4th period and 16th group of the periodic table.
Periodic Classification of Elements
Que 16. The electronic configuration of an element is 1s2 2s2 2p6 3s2 3p3. What is the atomic number of the element, which is just below the above element in the periodic table?
(1) 36 (2) 49 (3) 33 (4) 34
Ans 16. (3) 33
Reason: The electronic configuration belongs to elements Phosphorous and below it, Arsenic (As) exists with atomic number 33.
Que 17. Which of the following has the greatest electron affinity?
(1) I 2) Br (3) F (4) Cl
Ans 17. (4) Cl
Reason: It is due to the small size of the fluorine atom. As, there are strong inter electron repulsions in the relatively small 2P orbits of fluorine and thus, the incoming electron does not experience much attraction. Therefore, chlorine has an electron gain enthalpy than fluorine.
Que 18. Which one of the following is the correct order of the size of iodine species?
(1) I+ > I– > I (2) I– > I > I+
(3) I > I– > I+ (4) I > I+ > I–
Ans 18. (2) I– > I > I+
Reason: The size of the anion is larger than its parent atom and that of the cation is always smaller.
Que 19. The first ionization potentials (eV) of Be and B respectively are
(1) 8.29, 8.29 (2) 9.32, 9.32
(3) 8.29, 9.32 (4) 9.32, 8.29
Ans 19. (4) 9.32, 8.29
Reason: The ionization energy or ionization potential is the amount of energy required to remove an electron from an isolated atom or molecule. Be has higher potential due to fully filled 2s orbital (Be – 4 1s2, 2s2).
Que 20. Identify the correct order of the size of the following
(1) Ca2+ < K+ < Ar < Cl– < S2– (2) Ar < Ca2+ < K+ < Cl– < S2–
(3) Ca2+ < Ar < K+ < Cl– < S2– (4) Ca2+ < K+ < Ar < S2– < Cl–
Ans 20: (1) Ca2+ < K+ < Ar < Cl– < S2–
Reason: Among isoelectronic ions, ionic radii of anions is more than that of cations. Further size of the anion increases with an increase in negative charge and the size of the cation decreases with an increase in positive charge.
Periodic Classification of Elements
Que 21. The first ionization potential of Na, Mg, Al and Si are in the order
(a) Na < Mg > Al < Si (b) Na > Mg > Al > Si
(c) Na < Mg < Al > Si (d) Na > Mg > Al < Si
Ans 21. (a) Na < Mg > Al < Si
Reason: Removal of an electron from a stable, fully filled orbital requires more energy than removal of an electron from a partially filled orbital. Thus, ionisation enthalpy for Mg is greater than ionisation enthalpy for Al.
Que 22. The decreasing order of the ionisation potential in the following elements is
(a) Ne > Cl > P > S > Al > Mg (b) Ne > Cl > P > S > Mg > Al
(c) Ne > Cl > S > P > Mg > Al (d) Ne > Cl > S > P > Al > Mg
Ans 22. (b) Ne > Cl > P > S > Mg > Al
Que 23. Which of the following order is wrong
(a) NH3 < PH3 < AsH3 -acidic nature (b) Li+ < Na+ < K+ < Cs+ -ionic radius
(c) Al2O3 < MgO < Na2O < K2O -basic (d) Li < Be < B < C -1st ionisation potential
Ans 23. (d) Li < Be < B < C -1st ionisation potential
Que 24. The element with the highest electron affinity will belong to
(1) Period 2, group 17 (2) Period 3, group 17
(3) Period 2, group 18 (4) Period 2, group 1
Ans 24. (2) Period 3, group 17
Que 25. The correct order of electropositive nature of Li, Na and K is
(a) Li > Na > K (b) Li > K > Na
(c) Na > K > Li (d) K > Na > Li
Ans 25. (d) K > Na > Li
Reason: Electropositivity increases down the group in a periodic table because of an increase in size and decrease in ionisation enthalpy.
Que 26. Which one of the following oxides is neutral
(a) CO (b) SnO2 (c) ZnO (d) SiO2
Ans 26. (a) CO
Reason: oxides that neither react with acids or with bases are called neutral oxides.
Que 27. The strongest reducing agent is
(a) Cl2 (b) Cl– (c) Br– (d) I–
Ans 27. (d) I–
Reason: Tendency to lose electrons and reducing power is directly related to each other. Large-sized iodide ion has maximum tendency to lose electrons and has maximum reducing power.
Periodic Classification of Elements