Free NEET Chemistry multiple-choice questions on Trends in Atomic Properties. Attempt each question and reveal the answer with a full explanation.
Which element in the second period has the highest negative electron gain enthalpy? Fluorine Oxygen Neon Lithium The correct order of the metallic character in the periodic table is: Decreases across a period and increases down a group Increases across a period and decreases down a group Increases across a period and increases down a group Decreases across a period and decreases down a group Which of the following is the correct reason for the 'Inert Pair Effect' observed in heavy p-block elements? Poor shielding of ns 2 electrons by intervening d and f electrons. High electronegativity of the elements. Small size of the np orbitals. High effective nuclear charge of the np electrons only. In the periodic table, diagonal relationship is mainly due to similar: Ionic potential (charge/radius ratio) Atomic mass Number of valence electrons Group number What is the correct order of the hydration radii of the following ions? Li + > Na + > K + > Rb + Rb + > K + > Na + > Li + Li + = Na + = K + = Rb + Na + > Li + > K + > Rb + The first ionization enthalpy ( IE 1 ) of Magnesium is higher than that of Aluminum because: Magnesium has a stable fully-filled 3s orbital Aluminum has a higher nuclear charge than Magnesium The 3p electron in Aluminum is easier to remove than the 3s electron in Magnesium Magnesium has a smaller atomic radius than Aluminum Which of the following alkali metals has the lowest density? Lithium Sodium Potassium Rubidium Which of the following orders of solubility of Group 2 sulfates in water is correct? BeSO 4 > MgSO 4 > CaSO 4 > SrSO 4 > BaSO 4 BaSO 4 > SrSO 4 > CaSO 4 > MgSO 4 > BeSO 4 MgSO 4 > BeSO 4 > CaSO 4 > SrSO 4 > BaSO 4 CaSO 4 > MgSO 4 > BeSO 4 > SrSO 4 > BaSO 4 Which of the following elements has the largest atomic radius? Argon Chlorine Sulfur Phosphorus Compare the first ionization enthalpy ( IE 1 ) of Zinc ( Zn ) and Copper ( Cu ). Which is correct? IE 1 of Zn > IE 1 of Cu IE 1 of Cu > IE 1 of Zn IE 1 of Zn = IE 1 of Cu IE 1 of Cu is double that of Zn Boron shows a diagonal relationship with which element, and why? Silicon, due to similar charge/radius ratio Aluminum, because they are in the same group Magnesium, due to similar electronegativity Beryllium, due to similar size Which of the following is true regarding the first ionization enthalpy of Hydrogen and Helium? IE 1 of Helium is nearly double that of Hydrogen IE 1 of Hydrogen is greater than Helium IE 1 of Helium is less than Hydrogen Both have the same IE 1 as they are in the first period The correct order of atomic radii for the following species is: Mg > Mg + > Mg 2+ Mg 2+ > Mg + > Mg Mg + > Mg > Mg 2+ Mg > Mg 2+ > Mg + Compare the radii of Na + and F - . Which is correct? Na + < F - Na + > F - Na + = F - Radii cannot be compared as they belong to different periods The third ionization enthalpy ( IE 3 ) of Calcium is expected to be: Extremely high compared to IE 2 Slightly lower than IE 2 Lower than IE 1 The same as IE 2 In the third period of the periodic table, the atomic radius of Argon ( Ar ) is found to be significantly larger than that of Chlorine ( Cl ). This observation is best explained by which of the following? Van der Waals radius is measured for Argon, while covalent radius is measured for Chlorine Argon has a fully filled valence shell which increases inter-electronic repulsions The effective nuclear charge for Argon is lower than that of Chlorine Chlorine exists as a diatomic molecule, while Argon is monoatomic Which of the following sets represents the correct order of the acidic strength of oxyacids of group 15 elements? HNO 3 > H 3PO 4 > H 3As 4 > H 3SbO 4 H 3PO 4 > HNO 3 > H 3AsO 4 > H 3SbO 4 H 3SbO 4 > H 3AsO 4 > H 3PO 4 > HNO 3 HNO 3 > H 3AsO 4 > H 3PO 4 > H 3SbO 4 The successive ionization enthalpies for an unknown element X are: IE 1 = 578 kJ/mol, IE 2 = 1817 kJ/mol, IE 3 = 2745 kJ/mol, and IE 4 = 11578 kJ/mol. To which group does element X belong? Group 13 Group 2 Group 14 Group 15 The correct order of the basicity of the oxides of Group 15 elements is: Bi 2O 3 > Sb 2O 3 > As 2O 3 > P 2O 3 > N 2O 3 N 2O 3 > P 2O 3 > As 2O 3 > Sb 2O 3 > Bi 2O 3 P 2O 3 > N 2O 3 > As 2O 3 > Sb 2O 3 > Bi 2O 3 Bi 2O 3 > N 2O 3 > P 2O 3 > As 2O 3 > Sb 2O 3 In the context of periodic trends, which of the following elements has a positive electron gain enthalpy ( Δ eg H )? N O F C Which of the following elements has the highest density? Iridium ( Ir ) Osmium ( Os ) Gold ( Au ) Lead ( Pb ) The correct order of increasing first ionization enthalpy for O, S, F and Cl is: S < Cl < O < F S < O < Cl < F O < S < F < Cl Cl < S < F < O The valence shell electronic configuration of the element with the highest second ionization enthalpy in the second period is: 2s 2 2p 1 2s 1 2s 2 2s 2 2p 2 The noble gases have the highest ionization enthalpies in their respective periods because: They have stable fully filled electronic configurations They have small atomic sizes They have the highest effective nuclear charge Both (1) and (2) Which one of the following arrangements represents the correct order of electron gain enthalpy (with negative sign) of the given atomic species :- F < Cl < O < S S < O < Cl < F O < S < F < Cl Cl < F < S < O Identify the correct order of the size of the following: Ca 2+ < K+ < Ar < Cl - < S 2- Ar < Ca 2+ < K+ < Cl - < S 2- Ca 2+ < Ar < K+ < Cl - < S 2- Ca 2+ < K+ < Ar < S 2- < Cl - With which of the following electronic configuration an atom has the lowest ionisation enthalpy? 1s 2 2s 2 sp 3 1s 2 2s 2 2p 5 3s 1 1s 2 2s 2 2p 6 1s 2 2s 2 2p 5 In which of the following options the order of arrangement does not agree with the variation of property indicated against it ? Al 3+ < Mg 2+ < Na + < F - (increasing ionic size) B < C < N < O (increasing first ionisation enthalpy) I < Br < Cl < F (increasing electron gain enthalpy) Li < Na < K < Rb (increasing metallic radius) For the second period elements the correct increasing order of first ionisation enthalpy is: Li < Be < B < C < O < N < F < Ne Li < Be < B < C < N < O < F < Ne Li < B < Be < C < O < N < F < Ne Li < B < Be < C < N < O < F < Ne Identify the incorrect statement from the following The oxidation number of K in KO2 is +4. Ionisation enthalpy of alkali metals decreases from top to bottom in the group. Lithium is the strongest reducing agent among the alkali metals. Alkali metals react with water to form their hydroxides. Arrange the following elements in increasing order of first ionization enthalpy: Li, Be, B, C, N Choose the correct answer from the options given below: Li < Be < B < C < N Li < B < Be < C < N Li < Be < C < B < N Li < Be < N < B < C Which of the following statements are true? A. Unlike Ga that has a very high melting point, Cs has a very low melting point. B. On Pauling scale, the electronegativity values of N and Cl are not the same. C. Ar, K + , Cl - , Ca 2+ , and S 2- are all isoelectronic species. D. The correct order of the first ionization enthalpies of Na, Mg, Al, and Si is Si > Al > Mg > Na. E. The atomic radius of Cs is greater than that of Li and Rb. Choose the correct answer from the options given below : A, C, and E only A, B, and E only C and E only C and D only Identify the incorrect statement from the following: Oxygen exhibits only -2 oxidation state. The order of catenation property of Group 14 elements is C >> Si > Ge ≈ Sn. Carbon has the ability to form pπ-pπ multiple bond with itself. ECl3 (E = B and Al) is a monomer when E = B and a dimer when E = Al. Identify the incorrect statement from the following : The largest and the smallest species among Mg, Mg 2+ , Al and Al 3+ are Al and Mg 2+ respectively. The IUPAC name of the element with atomic number 107 is Unnilseptium. The similarity in behaviour of Li with Mg is referred to as ‘diagonal relationship’ The oxidation state and covalency of Al in [AlCl(H2O)5] 2+ are 3 and 6 respectively. Van der Waals radii are usually: Larger than covalent radii Smaller than covalent radii Equal to covalent radii Half of the ionic radii The formation of the oxide ion, O 2- (g) , from oxygen atom requires first an exothermic and then an endothermic step as shown below: O(g) + e - O -(g); h H = -141 kJ mol -1 O -(g) + e - O 2- (g); h H = +780 kJ mol -1 Thus process of formation of O 2- in gas phase is unfavorable even though O 2- is isoelectronic with neon. It is due to the fact that: Electron repulsion outweighs the stability gained by achieving noble gas configuration O - ion has comparatively smaller size than oxygen atom Oxygen is more electronegative Addition of electron in oxygen results in larger size of the ion The correct order of decreasing second ionization enthalpy of Ti(22), V(23), Cr(24) and Mn(25) is: Cr > Mn > V > Ti Mn > Cr > Ti > V Ti > V > Cr > Mn V > Mn > Cr > Ti Which of the following is the correct order of electron gain enthalpy (with negative sign) for O, S, Se, Te ? S > Se > Te > O O > S > Se > Te S > O > Se > Te Te > Se > S > O Which of the following transitions involves maximum energy absorption? He + He 2+ + e - He He + + e - H H + + e - Li + Li 2+ + e - The ionic radius of Ga 3+ is smaller than that of Al 3+ despite being below it in the periodic table. This is primarily due to: Poor shielding by 3d electrons The presence of 4p electrons Lanthanoid contraction Greater number of protons Identify the element with the highest second ionization enthalpy among the following: Li Be B C Which of the following has the highest value of second ionization enthalpy? Cu Zn Cr Mn The order of non-metallic character among B, C, Si, N and F is: B < Si < C < N < F Si < B < C < N < F F < N < C < B < Si B < C < Si < N < F The radius of La 3+ (Atomic number 57) is 1.06 . Which of the following given values will be closest to the radius of Lu 3+ (Atomic number 71)? 0.85 1.60 1.40 1.06 The element with the highest second ionization enthalpy in the first transition series is: Cu Cr Mn Fe Which of the following is the correct order of ionic radii for isoelectronic species? N 3- > O 2- > F - > Na + Na + > F - > O 2- > N 3- O 2- > N 3- > F - > Na + F - > Na + > O 2- > N 3- The ionic mobility of alkali metal ions in aqueous solution follows the order: Li + < Na + < K + < Rb + < Cs + Cs + < Rb + < K + < Na + < Li + Li + < K + < Na + < Rb + < Cs + Rb + < Cs + < K + < Na + < Li + Which of the following orders is correct for the first ionization enthalpy ( IE 1 ) of Group 13 elements? B > Tl > Ga > Al > In B > Al > Ga > In > Tl B > Ga > Al > In > Tl Tl > B > Ga > Al > In The correct order of increasing second ionization enthalpy ( IE 2 ) for the elements O, N, F and C is: C < N < F < O C < N < O < F O < N < F < C F < O < N < C Which of the following gaseous ions has the highest value of ionic radius? H - F - Li + Be 2+ The first ionization enthalpy of Pb (Lead) is slightly higher than that of Sn (Tin). This anomaly is due to: Poor shielding effect of 4f electrons Increased metallic character Inert pair effect Smaller atomic size of Pb The screening constant ( ) for a 4s electron in Potassium ( K, Z=19 ) according to Slater's rules is: 16.80 17.20 2.20 18.00 Which of the following is the correct order of the size of the hydride ion ( H - ) compared to F - and Cl - ? Cl - > H - > F - H - > Cl - > F - Cl - > F - > H - H - > F - > Cl - The relationship between Electron Affinity ( EA ) and Electron Gain Enthalpy ( Δ eg H ) at absolute zero is: EA = -Δ eg H EA = Δ eg H EA = Δ eg H + 5 2 RT EA = Δ eg H - 5 2 RT Lithium and Magnesium show a diagonal relationship. Which of the following properties is NOT similar for both? Both form peroxides and superoxides on heating in excess air Both form nitrides by direct combination with Nitrogen Their carbonates decompose on heating to give oxides and CO 2 Both their chlorides are deliquescent Comparing the first ionization enthalpies of Gold ( Au, Z=79 ) and Mercury ( Hg, Z=80 ), which statement is true? IE 1 of Hg is higher than Au due to the stable 6s 2 configuration IE 1 of Au is higher than Hg due to the Lanthanoid contraction IE 1 of Hg is lower than Au because Hg is a liquid Both have identical IE 1 values Which of the following elements has the highest negative electron gain enthalpy? Cl F Br I Calculate the effective nuclear charge ( Z eff ) for the valence electron of a Carbon atom ( Z=6 ) using Slater's Rules. 3.25 2.75 4.00 2.25 Calculate the effective nuclear charge ( Z eff ) for a 2p electron in a Fluorine atom ( Z = 9 ) using Slater's rules. 5.20 4.55 9.00 2.60 Which statement correctly compares the first ionization enthalpies of Zinc ( Zn ) and Copper ( Cu )? IE 1 of Zn is higher than IE 1 of Cu because Zn has a stable 4s 2 configuration IE 1 of Cu is higher than IE 1 of Zn because Cu has a 3d 10 configuration Both have identical IE 1 as they belong to the same period IE 1 of Zn is lower than IE 1 of Cu due to better shielding Which of the following is the correct order of the second ionization enthalpy ( IE 2 )? Li > Ne > O > N Ne > Li > O > N Li > O > N > Ne O > N > F > Ne Calculate the effective nuclear charge ( Z eff ) for the outermost 4s electron in Calcium ( Z=20 ) using Slater's rules. 2.85 3.50 4.15 2.20 The correct order of density for alkali metals is: Li < K < Na < Rb < Cs Li < Na < K < Rb < Cs Cs < Rb < K < Na < Li K < Li < Na < Rb < Cs The element with the highest third ionization enthalpy ( IE 3 ) among the following is: Magnesium Aluminum Calcium Barium Using Slater's rules, calculate the shielding constant ( ) for the valence 2s electron in a Lithium atom ( Z = 3 ). 1.70 0.85 0.30 2.05 Which of the following pairs shows the correct comparison of second ionization enthalpies ( IE 2 )? IE 2 of K > IE 2 of Ca IE 2 of Mg > IE 2 of Na IE 2 of O < IE 2 of N IE 2 of F > IE 2 of O Comparing the second ionization enthalpy ( IE 2 ) of Oxygen and Fluorine, which statement is true? IE 2 of Oxygen is greater than that of Fluorine IE 2 of Fluorine is greater than that of Oxygen Both have identical IE 2 values IE 2 cannot be compared for these two elements The species Ar, K + and Ca 2+ contain the same number of electrons. In which order do their radii increase? Ca 2+ < K + < Ar Ar < K + < Ca 2+ K + < Ar < Ca 2+ Ca 2+ < Ar < K + Using Slater's rules, calculate the effective nuclear charge ( Z eff ) for a 3d electron in a Scandium ( Sc, Z=21 ) atom. 3.00 2.10 18.00 3.90 Which of the following transitions involves the greatest increase in effective nuclear charge ( Z eff ) per electron for s -block elements? Li to Be Na to Mg K to Ca Rb to Sr Among the following options, the correct trend in the electron gain enthalpy is F > Cl > Br > I Br > Cl > F > I Cl > F > Br > I I > Br > Cl > F Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R. Assertion A: The first ionization enthalpy of O is lower than that of N and F. Reason R: The loss of an electron from O leads to stable half-filled p orbital In light of the above statements, choose the most appropriate answer from the options given below: Both A and R are correct and R is the correct explanation of A Both A and R are correct and R is NOT the correct explanation of A A is correct but R is not correct. A is not correct but R is correct Which of the following is the correct order of increasing ionic radii of O 2- , F -, Na + and Mg 2+ ? Mg 2+ < Na + < F - < O 2- O 2- < F - < Na + < Mg 2+ Na + < Mg 2+ < F - < O 2- F - < Na + < Mg 2+ < O 2- The diagonal relationship between Lithium and Magnesium is due to: Similar ionic sizes and high electronegativity Same number of valence electrons Similar crystal structures Identical electronic configurations The correct sequence of the screening effect of s, p, d, f subshells on the valence electrons is: s > p > d > f f > d > p > s p > s > d > f d > f > s > p Which of the following species has the smallest size? H + H H - He Which of the following is the most electropositive element? Cs Li Na K Which transition in a hydrogen-like atom involves the absorption of the most energy, relating to the trend of ionization? n=1 n=∞ n=2 n=∞ n=1 n=2 n=2 n=3 The first ionization enthalpy of Be is higher than that of B because: Be has a stable fully filled 2s 2 subshell B has a higher nuclear charge than Be The 2p electron is more strongly held than the 2s electron Be is a metal while B is a metalloid Which of the following has the smallest size? Al 3+ Mg 2+ Na + F - Which of the following elements has the lowest first ionization enthalpy? Ba Ca Mg Sr Which of the following is the correct order of the size of the given species? I - > I > I + I + > I > I - I > I - > I + I > I + > I - Which of the following atoms has the lowest value of first ionization enthalpy? Cs Rb K Na In the third period of the periodic table, the element with the highest first ionization enthalpy is: Argon Chlorine Phosphorus Sulfur The electron gain enthalpy of noble gases is: Large positive Large negative Small negative Zero Which of the following transitions in a neutral gaseous atom A requires the least energy? A(g) A +(g) + e - A +(g) A 2+ (g) + e - A 2+ (g) A 3+ (g) + e - A 3+ (g) A 4+ (g) + e - The correct order of increasing radii for the types of atomic radii in a metal like Copper is: Covalent radius < Metallic radius < Van der Waals radius Metallic radius < Covalent radius < Van der Waals radius Van der Waals radius < Metallic radius < Covalent radius Covalent radius < Van der Waals radius < Metallic radius Which of the following elements has the lowest density? Lithium ( Li ) Sodium ( Na ) Potassium ( K ) Rubidium ( Rb ) What is the correct order of the radii for the following iron species? Fe > Fe 2+ > Fe 3+ Fe 3+ > Fe 2+ > Fe Fe 2+ > Fe 3+ > Fe Fe > Fe 3+ > Fe 2+ Which of the following noble gases has the highest first ionization enthalpy? Helium Neon Argon Radon Which group of elements has the highest negative electron gain enthalpy in the periodic table? Group 17 (Halogens) Group 16 (Chalcogens) Group 18 (Noble Gases) Group 1 (Alkali Metals) How does the electronegativity ( χ ) of an atom generally relate to its atomic radius ( r )? χ ∝ 1/r χ ∝ r χ ∝ r 2 χ ∝ 1/r 2 The covalent radius of an element is always shorter than its corresponding Van der Waals radius because: Covalent bonds involve the overlap of atomic orbitals Van der Waals forces are stronger than covalent bonds Covalent radii are measured in the gaseous state Van der Waals radii involve shared electrons For any element, the correct order of successive ionization enthalpies is: IE 1 < IE 2 < IE 3 IE 1 > IE 2 > IE 3 IE 1 < IE 2 > IE 3 IE 1 = IE 2 = IE 3 The diagonal relationship is shown by: Li and Mg Li and Be Be and Mg B and Mg Which of the following ions has the smallest radius? Fe 3+ Fe 2+ Fe Mn 2+ If the inter-nuclear distance between two Chlorine atoms in Cl 2 is 198 pm, the covalent radius of Chlorine is: 99 pm 198 pm 396 pm 180 pm Which of the following properties is NOT a periodic property (does not show a regular trend in the periodic table)? Radioactivity Ionization Enthalpy Valency Atomic Radius Which of the following represents the correct trend of boiling points for halogens? F 2 < Cl 2 < Br 2 < I 2 I 2 < Br 2 < Cl 2 < F 2 F 2 < Br 2 < Cl 2 < I 2 Cl 2 < F 2 < Br 2 < I 2 The first ionization enthalpy of Nitrogen ( 1402 kJ/mol ) is higher than that of Oxygen ( 1314 kJ/mol ). Which of the following is the best explanation? Extra stability of half-filled 2p orbitals in Nitrogen. Higher electronegativity of Nitrogen compared to Oxygen. Smaller atomic radius of Nitrogen compared to Oxygen. Increased electron-electron repulsion in the 2p shell of Oxygen. Which of the following ions is expected to have the largest ionic radius? N 3- O 2- F - Na + For which of the following elements does the valence electron experience the highest shielding effect? Cesium Lithium Sodium Potassium What is the correct order of the size of iodine species? I - > I > I + I > I - > I + I + > I > I - I - > I + > I Which of the following gaseous atoms has the highest value of first ionization enthalpy? He Ne Ar Kr Which of the following elements has the lowest melting point? Mercury Gallium Cesium Sodium In Group 15, the metallic character increases down the group. Which element is considered a typical metal? Bismuth Antimony Arsenic Phosphorus The ionic radius of N 3- is larger than P 3- : True or False? False True They are equal Depends on the solvent Amongst the element with following electronic configurations, which one of them may have the highest ionization energy ? [Ne]3s 2 3p 1 [Ne]3s 2 3p 3 [Ne]3s 2 3p 2 [Ar]3d 10 4s 2 4p 3 Calculate the screening constant ( ) for the 1s electron in a Hydrogen atom according to Slater's rules. 0 0.30 0.35 1.00 Which of the following orders of ionic radii is correctly represented ? H - > H + > H Na + > F - > O 2- F - > O 2- > Na + Al 3+ > Mg 2+ > N 3- Which of the following oxides is most acidic in nature? BaO BeO MgO CaO The correct sequence of bond enthalpy of 'C—X' bond is : CH3-F > CH3-Cl > CH3-Br > CH3-I CH3-F < CH3-Cl > CH3-Br > CH3-I CH3-Cl > CH3-F > CH3-Br > CH3-I CH3-F < CH3-Cl < CH3-Br < CH3-I The element expected to form largest ion to achieve the nearest noble gas configuration is O F N Na The correct order of increasing metallic character of Na, Be, P, Mg and Si is Be < Si < P < Mg < Na P < Si < Na < Mg < Be P < Si < Be < Mg < Na P < Mg < Be < Si < Na The correct order of atomic radii in group 13 elements is: B < Ga < Al < In < Tl B < Al < Ga < In < Tl B < Al < In < Ga < Tl B < Ga < Al < Tl < In The screening effect of d -electrons is: Less than p -electrons Equal to p -electrons More than p -electrons Equal to s -electrons Which factor is mostly responsible for the similarity in properties of Zr and Hf ? Lanthanoid contraction Diagonal relationship Inert pair effect Same group properties For the second period elements, the correct increasing order of first ionization enthalpy is: Li < B < Be < C < O < N < F < Ne Li < Be < B < C < N < O < F < Ne Li < B < Be < C < N < O < F < Ne Li < Be < B < C < O < N < F < Ne Which of the following processes involves the largest amount of energy? Mg +(g) Mg 2+ (g) + e - Mg(g) Mg +(g) + e - Al(g) Al +(g) + e - Na(g) Na +(g) + e - Identify the correct order of the size of atoms/ions for the halogen species: I - > I > I + I + > I > I - I > I + > I - I - > I + > I Which of the following property strictly increases from left to right in a period? Effective nuclear charge ( Z eff ) Atomic radius Metallic character Ionic radius Which of the following atoms has the highest first ionization enthalpy? Sc Ti V Cr The correct order of electron gain enthalpy with negative sign for the chalcogens is: S > Se > Te > O O > S > Se > Te Te > Se > S > O S > O > Se > Te Which of the following is the correct order of increasing size of isoelectronic species? Ca 2+ < K + < Ar < Cl - < S 2- Ar < Ca 2+ < K + < Cl - < S 2- Ca 2+ < Ar < K + < Cl - < S 2- Ca 2+ < K + < Ar < S 2- < Cl - The first ionization enthalpies of Na, Mg, Al and Si are in the order: Na < Al < Mg < Si Na < Mg < Al < Si Na > Mg > Al > Si Al < Na < Mg < Si In which of the following arrangements, the order is NOT according to the property indicated against it? Li < Be < B < C (First Ionization Enthalpy) I < Br < Cl < F (Electronegativity) Al 3+ < Mg 2+ < Na + < F - (Ionic size) B < C < N < O (Atomic radius decreases) Considering the elements B, Al, Mg, and K , the correct order of their metallic character is: K > Mg > Al > B Mg > Al > K > B Al > Mg > B > K K > Al > Mg > B In the context of the periodic table, which of the following statements is true regarding the screening effect? The screening effect of s -electrons is greater than that of p -electrons The screening effect of d -electrons is greater than that of p -electrons The screening effect of f -electrons is the most effective Screening effect decreases with an increase in the number of inner shells Which of the following transitions results in the release of maximum energy? Cl(g) + e - Cl -(g) O(g) + e - O -(g) F(g) + e - F -(g) S(g) + e - S -(g) The correct order of the first ionization enthalpy for the elements N, O, F and Ne is: O < N < F < Ne N < O < F < Ne O < F < N < Ne F < O < N < Ne Which of the following elements has the lowest boiling point? Helium ( He ) Hydrogen ( H 2 ) Neon ( Ne ) Argon ( Ar ) Among the elements with the following electronic configurations, which one would have the highest ionization enthalpy? [Ne] 3s 2 3p 3 [Ne] 3s 2 3p 2 [Ar] 3d 10 4s 2 4p 3 [Ne] 3s 2 3p 1 Which of the following represents the correct order of electron affinity? O < S < F < Cl S < O < Cl < F O < S < Cl < F S < O < F < Cl The electron gain enthalpy (with negative sign) is higher for Chlorine than for Fluorine. The correct reason for this anomaly is: The small size of the Fluorine atom leads to high inter-electronic repulsion in its relatively compact 2p subshell. Chlorine has a higher electronegativity than Fluorine on the Pauling scale. The 3p orbital of Chlorine is more screened than the 2p orbital of Fluorine. Fluorine is a gas while Chlorine is a liquid at room temperature. Which of the following arrangements represents the correct order of increasing basic nature of the oxides? Al 2O 3 < MgO < Na 2O < K 2O MgO < Al 2O 3 < K 2O < Na 2O Na 2O < K 2O < MgO < Al 2O 3 K 2O < Na 2O < MgO < Al 2O 3 The effective nuclear charge ( Z eff ) experienced by valence electrons in an atom: Increases across a period from left to right. Decreases across a period from left to right. Remains constant across a period. Is always equal to the total number of protons. The diagonal relationship of Boron ( B ) is with which element? Silicon ( Si ) Aluminum ( Al ) Magnesium ( Mg ) Beryllium ( Be ) Which of the following has the largest ionic radius? N 3- O 2- F - Na + The screening effect of d -electrons is less than that of p -electrons because: d -orbitals are more diffused in space than p -orbitals. d -orbitals have higher energy than p -orbitals. d -orbitals are closer to the nucleus. d -orbitals are spherical in shape. Based on the following successive ionization enthalpies (in kJ/mol ): IE 1 = 496, IE 2 = 4562, IE 3 = 6910 , the element is most likely to be: Sodium ( Na ) Magnesium ( Mg ) Aluminum ( Al ) Silicon ( Si ) Identify the correct order of increasing ionic radii among the isoelectronic species N 3- , O 2- , F - and Na + : Na + < F - < O 2- < N 3- N 3- < O 2- < F - < Na + F - < Na + < O 2- < N 3- Na + < O 2- < F - < N 3- The correct order of the covalent radii of C, N, O and F is: C > N > O > F F > O > N > C C < N < O < F N > C > O > F Which of the following properties shows a decrease as we move down Group 1 (Alkali metals)? Melting point Atomic radius Density Ionic radius The second ionization enthalpy ( IE 2 ) of Sodium ( Na ) is significantly higher than that of Magnesium ( Mg ) because: In Na + , the electron is removed from a stable noble gas configuration In Mg + , the electron is removed from a half-filled orbital Sodium has a higher nuclear charge than Magnesium The atomic size of Magnesium is larger than Sodium Nitrogen ( Z=7 ) has a higher first ionization enthalpy than Oxygen ( Z=8 ). This is due to: Extra stability of the half-filled 2p 3 subshell in Nitrogen Higher nuclear charge of Nitrogen Smaller atomic radius of Nitrogen Greater screening effect in Oxygen The effective nuclear charge ( Z eff ) across a period in the modern periodic table: Increases as the number of protons increases while shielding increases slowly Decreases because the number of shells increases Remains constant for all elements in the same period Increases as the number of shells increases Between Phosphorus ( Z=15 ) and Sulfur ( Z=16 ), which one has a higher first ionization enthalpy ( IE 1 ) and why? Phosphorus, due to its stable half-filled 3p 3 configuration Sulfur, due to its higher nuclear charge Phosphorus, because it is smaller in size than Sulfur Sulfur, because it has more electrons in the valence shell The basicity of the hydroxides of alkali metals follows the order: LiOH < NaOH < KOH < RbOH < CsOH CsOH < RbOH < KOH < NaOH < LiOH NaOH < LiOH < KOH < RbOH < CsOH LiOH < NaOH < KOH < CsOH < RbOH Arrange the following isoelectronic species in increasing order of their radii: P 3- , S 2- , Cl -, Ar, K +, Ca 2+ . Ca 2+ < K + < Ar < Cl - < S 2- < P 3- P 3- < S 2- < Cl - < Ar < K + < Ca 2+ Ar < Cl - < S 2- < P 3- < K + < Ca 2+ Ca 2+ < K + < Cl - < S 2- < P 3- < Ar The first ionization enthalpy of Gallium is slightly higher than that of Aluminum. The correct reason is: Poor shielding of the nucleus by the 3d electrons in Gallium Gallium has a smaller atomic radius than Aluminum Gallium has a higher atomic weight than Aluminum Aluminum has a more stable electronic configuration The hydration enthalpy of alkali metal ions follows the order: Li + > Na + > K + > Rb + > Cs + Cs + > Rb + > K + > Na + > Li + Li + > K + > Na + > Rb + > Cs + Na + > Li + > K + > Rb + > Cs + Which of the following pairs of elements have nearly identical atomic radii due to Lanthanoid contraction? Nb and Ta Zr and Nb Mo and W Ti and Zr In which of the following pairs, both species are not isoelectronic? Mg 2+ , Ar O 2- , F - Na +, Mg 2+ N 3- , Ne The third ionization enthalpy ( IE 3 ) of Magnesium ( Mg ) is exceptionally high because: The third electron must be removed from a stable noble gas configuration ( 2p 6 ) The effective nuclear charge decreases after removing two electrons Magnesium has a small atomic size in its group The 3s orbital is completely filled Which of the following alkali metals has a lower density than the element immediately preceding it in Group 1? Potassium ( K ) Sodium ( Na ) Rubidium ( Rb ) Cesium ( Cs ) Among the following, which element has the least negative electron gain enthalpy? Oxygen ( O ) Sulfur ( S ) Selenium ( Se ) Tellurium ( Te ) The oxide Mn 2O 7 is X , whereas MnO is Y . Identify X and Y . X = Acidic, Y = Basic X = Basic, Y = Acidic X = Amphoteric, Y = Basic X = Neutral, Y = Basic The melting points of alkali metals decrease down the group because: The strength of metallic bonding decreases with increasing atomic size The number of valence electrons increases The ionization enthalpy increases The density increases In Lothar Meyer's atomic volume curve, which elements occupy the positions at the peaks? Alkali metals Alkaline earth metals Halogens Noble gases What is the shielding constant ( ) for a 1s electron in a Helium atom according to Slater's rules? 0.30 0.35 0.85 1.00 Which of the following alkali metal ions has the highest degree of hydration in aqueous solution? Li + Na + K + Cs + Which of the following atoms has the lowest electron affinity (least negative electron gain enthalpy)? Nitrogen Oxygen Carbon Boron Which of the following is the most powerful oxidizing agent among the halogens in aqueous solution? F 2 Cl 2 Br 2 I 2