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Practice each question, then open the answer or worked solution.
Which of the following elements can show covalency greater than 4?
(i) Be
(ii) P
(iii) S
(iv) B
Ans: (ii) & (iii)
Both P and S have vacant d-orbital for which they execute extended covalency.
Those elements impart colour to the flame on heating in it, the atoms of which require low energy for the ionisation (i.e., absorb energy in the visible region of spectrum). The elements of which of the following groups will impart colour to the flame?
(i) 2
(ii) 13
(iii) 1
(iv) 17
Ans: (i)&(iii)
Alkali metals and alkaline earth metals have low ionization enthalpy.
Which of the following sequences contain atomic numbers of only representative elements?
(i) 3, 33, 53, 87
(ii) 2, 10, 22, 36
(iii) 7, 17, 25, 37, 48
(iv) 9, 35, 51, 88
Ans: (i)&(iv)
The s-block elements and p-block elements together are called representative elements.
Which of the following elements will gain one electron more readily in comparison to other elements of their group?
(i) S (g)
(ii) Na (g)
(iii) O (g)
(iv) Cl (g)
Ans: (i)&(iv)
Both S and Cl have the higher tendency to gain electrons in order to attain stable nearest noble gas configuration i.e. of Argon.
Which of the following statements are correct?
(i) Helium has the highest first ionisation enthalpy in the periodic table.
(ii) Chlorine has less negative electron gain enthalpy than fluorine.
(iii) Mercury and bromine are liquids at room temperature.
(iv) In any period, atomic radius of alkali metal is the highest.
Ans: (i),(iii)&(iv)
He with 1s2 electronic configuration has the highest electron gain enthalpy in the periodic table.
In any period the alkali metals have lowest effective nuclear charge in that particular period for which its atomic radius is highest in that period.
Which of the following sets contain only isoelectronic ions?
(i) Zn2+, Ca2+, Ga3+, Al3+
(ii) K+ , Ca2+, Sc3+, Cl –
(iii) P3–, S2–, Cl– , K+
(iv) Ti 4+, Ar, Cr3+, V5+
Ans: (ii)&(iii)
Isoelectronic species/ions are those species that possess the same number of electrons.
In which of the following options order of arrangement does not agree with the variation of property indicated against it?
(i) Al3+ < Mg2+ < Na+ < F– (increasing ionic size)
(ii) B < C < N < O (increasing first ionisation enthalpy)
(iii) I < Br < Cl < F (increasing electron gain enthalpy)
(iv) Li < Na < K < Rb (increasing metallic radius)
Ans: (ii)&(iii)
The ionization enthalpy of N is higher than that of F because it possess half filled orbital which provide it extra stability due to symmetry
As the atomic size of F is much smaller thus its electron gain enthalpy is lower than that of the Cl
Which of the following have no unit?
(i) Electronegativity
(ii) Electron gain enthalpy
(iii) Ionisation enthalpy
(iv) Metallic character
Ans: (i)&(iv)
Both electronegativity and metallic character do not possess units as they both are qualitative properties not a quantitative property.
Ionic radii vary in
(i) inverse proportion to the effective nuclear charge.
(ii) inverse proportion to the square of effective nuclear charge.
(iii) direct proportion to the screening effect.
(iv) direct proportion to the square of screening effect.
Ans: (i)&(iii)
Ionic radii decreases with the increase of the effective nuclear charge and increases with the increase of shielding effect or e--e- repulsion as it outweighs the effective nuclear charge effect.
An element belongs to 3rd period and group-13 of the periodic table. Which of the following properties will be shown by the element?
(i) Good conductor of electricity
(ii) Liquid, metallic
(iii) Solid, metallic
(iv) Solid, non metallic
Ans:(i)&(iii)
Aluminium is the element which is a metal and good conductor of electricity.