CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES

CLASSIFICATION OF ELEMENTS AND PERIODICITY IN PROPERTIES Quiz -22

Dear Readers,

JEE Advanced is a high level exam that checks your concept by putting various types of questions. The questions are in a different format from JEE mains.m, herein the questions are : single correct multiple choice questions, multiple correct multiple choice questions, statement based questions and comprehension type questions.

Matrix-Match Type

This section contain(s) 10 question(s). Each question contains Statements given in 2 columns which have to be matched. Statements (A, B, C, D) in columns I have to be matched with Statements (p, q, r, s) in columns II.

Q1. Ionic radius is the effective distance from the nucleus of an ion up to which it has its influence on its electron cloud. A cation is always much smaller than the corresponding atom. Further more the number of electrons removed, smaller will be the size of the resulting positive ion. For example r_Fe>r_(Fe^(2+) )>r_(Fe^(3+) ) A cation formed by the loss of electrons may result in the complete disappearance of the outer shell and since, the remaining inner shells do not extend so far in space, the cation is much smaller than the metal atom. For example In case of isoelectronic ions, the greater the nuclear charge, the greater is the attraction for electrons and smaller is ionic radius 253. The size of the species Pb,Pb^(2+) and Pb^(4+) decreases as

•  Pb^(4+)>Pb^(2+)>Pb
•   Pb>Pb^(2+)>Pb^(4+)
•   Pb^(4+)>Pb>Pb^(2+)
•   Pb^(2+)>Pb^(4+)>Pb

Solution. (c)

Q2. Just as energy is required to remove an electron from an atom, energy is generally released when an electron is added to a neutral atom. When an electron is added to a neutral gaseous atom to convert it into a negative ion, the enthalpy change accompanying the process is called the electron gain enthalpy (∆_eg H). It provides a quantitative measure of the ease with which an atom adds an electron to form anion X(g)+e^-→X^- (g)+ Energy Electron gain enthalpy, like ionisation potential, is expressed in electron volt/atom or kcal/mol or kJ/mol. Electron gain enthalpy of chlorine is -349 kJ/mol. This means that 349 kJ of energy is released when one mole of chlorine atoms (6.02×〖10〗^23 atoms) change into Cl^- ions Cl(g)+e^-→Cl^- (g)+349 kJ Cl(g)+e^-→Cl^- (g) ∆_eg H=-349 kJ mol^(-1) 254. Second electron gain enthalpy

•  Can be positive or negative
•  Is always zero
•  Is always negative (energy is released)
•   Is always positive (energy is absorbed)

Solution.
(a)

Q3.  Following questions are based on Sc(Z=21) 255. Out of Sc^(3+),Sc^(2+) and Sc^+ paramagnetic as well coloured ions are

•   Sc^+,Sc^(2+)
•  Sc^+,Sc^(3+)
•  Sc^(2+),Sc^(3+)
•  All being d-block element

Solution. (d)

Q4.  Following rule in general, classifies p-block elements into metals, non-metals and metalloids (where P is the period and N the valence electrons) (P+1)>N, the element would be metal (P+1)

•  13
•  14
•  15
•  16

Solution (b)

Q5. In the following table I_1,I_2 and I_3 of the main group elements in 2nd period have been given Li Be B C N O F Ne I_1 I_2 I_3 513 729 8 118 15 899 175 7 148 48 801 242 7 366 0 108 6 235 2 462 0 140 2 285 6 457 8 131 4 338 8 530 0 168 1 337 4 605 0 208 0 395 2 612 2 Answer the following questions based on the above table 257. There is increase in ionization energy along a period going Li to Ne, but I_1 of B is less than that of Be. This is due to

•  Valence electron in B is in 2p-orbital of higher energy than that of Be in 2s-orbital of lower energy
•  Removal of paired electron in Be requires higher energy than that of removal of unpaired electron in B
•   Both (a) and (b) above
•   None of the above

Solution  (b)

Q6. The sums of first and second ionization energies and those of third and fourth ionization energies (in MJ mol^(-1)) of nickel and platinum are (IE)_1+(IE)_2 (IE)_2+(IE)_4 Ni Pt 2.49 2.66 8.80 6.70 Based on this information, answer the following questions 258. Most common oxidation states of Ni and Pt are respectively

•  +2,+2
•   +4,+2
• +2,+4
•  +4,+4

Solution. (d)

Q7.The 〖(IE)〗_1 and the 〖(IE)〗_2 on kJ mol^(-1) of a few elements designated by Roman numerals are shown below Element (IE)_1 (IE)_2 A B C D 2372 520 900 1680 5251 7300 1760 3380 Based on the above information, answer the following questions 259. Which of the above elements is likely to be a reactive metal?

•  A
•  B
•  C
•   D

Solution
(a)

Q8.Consider the following table comparing ionic radius Ion → N^(3-) O^(2-) F^- Na^+ Mg^(2+) Number of electron Number of nuclear protons Ionic radius (pm) 10 7 146 10 8 140 10 9 133 10 11 98 10 12 79 Answer the following questions. 260. Select the correct alternate(s) in term of size

•  Na>Na^+
•  Mg>Mg^+>Mg^(2+)
•   F^->F
•   O^(2-)>O^->O

Solution
(b)

Q9.The heats of formation (∆H_f°) of the oxides of the third period, sodium to chlorine, are in kJ mol^(-1) Na_2 O MgO Al_2 O_3 SiO_2 P_4 O_10 SO_3 Cl_2 O_7 -416 -602 -1676 -911 -2984 -395 +250 Based on these data, answer the following questions 261. Which oxide has maximum negative heat of formation per oxygen atom? a) P_4 O_10 b) Al_2 O_3 c) Na_2 O d) MgO

•  P_4 O_10
•   Al_2 O_3
•   Na_2 O
•  MgO

Solution
(a) AB_2 has bcc structure, A^(2+) possess face centred cubic lattice. B^- ions occupy all the (100%) tetrahedral voids. Thus each A^(2+) is in contact with B^- and each B^- with 4A^(2+) ions.

Q10.The singly-bonded metallic radius of Na is 157 pm. Assume that the increment between radii of different magnitudes is 60 pm Answer the following questions 262. The covalent radius of Na is

•  157pm
•   97pm
•  217pm
•  297pm

Solution
(b) All factual statements