Classification of Elements and Periodicity in Properties
Exam Duration: 45 Mins Total Questions : 30
Which basic concept was used by Mendeleef for organising the elements?
- (a)
He organised the metals only
- (b)
He organised the non-metals only
- (c)
He organised the both metals and non-metals according to increasing number of masses
- (d)
None of the above
Mendeleef observed that the periodic properties of elements are periodic function of atomic masses.
The period number in the long form of the periodic table is equal to
- (a)
magnetic quantum number of any element of the period
- (b)
atomic number of any element of the period
- (c)
maximum principal quantum number of any element of the period
- (d)
maximum azimuthal quantum number of any element of the period
maximum value of principal quantum number denotes the valence shell which is equivalent to the period number.
What will be the IUPAC name of element having Z=106?
- (a)
Unniquadium
- (b)
Unnilhexium
- (c)
Unnilheptium
- (d)
Ununhexium
For Z=106
Root of 1-un
Root of 0-nil
Root of 6-hex+ium
IUPAC name=unnihexium
The element with atomic number 35, 53 and 85 are all.....
- (a)
noble gases
- (b)
halogens
- (c)
heavy metals
- (d)
light metals
Halogens, because all have ns2np5 electronic configuration
Which of the following group elements belongs to chalcogens?
- (a)
N, P, As, Sb, Bi
- (b)
C, Si, Ge, Sn, Pb
- (c)
O,S,Se,Te, Po
- (d)
He, Ne, Ar, Kr, Xe, Rn
All elements belongs to group 16 are called chalcogens.
Consider the isoelectronic species Na+, Mg2+, F- and O2-. The correct increasing order of their radii is .....
- (a)
F- < O2- < Mg2+ < Na+
- (b)
Mg2+ < Na+ < F- < O2-
- (c)
O2-<F-<Na+<Mg2+
- (d)
O2- < F- < Mg2+ < Na+
In case of isoelectronic species, greater the charge on cation, smaller the size and greater the charge on anion, larger the size
Which of the following represents correct order of first ionisation energy?
- (a)
K > Na > Li
- (b)
Be > Mg > Ca
- (c)
B > C > N
- (d)
Ce > Si > C
Be has electronic configuration = 1s2, 2s2
Mg has electronic configuration = [Ne]3s2
Ca has electronic configuration =[Ar]4s2
Lower value of n represents higher value of IE due to smaller size of element
Which of the following has lowest value of ionisation energy?
- (a)
Mg
- (b)
Ca
- (c)
Ba
- (d)
Sr
Because Ba has highest value of principal quantum number among all hence, it is easier to remove electron from its valence shell.
The IE will be minimum for
- (a)
N
- (b)
P
- (c)
Al
- (d)
B
N=1s2, 2s2, 2p3
It has extra stable half-filled electronic configuration.
So, high value of IE1
Which of the following has highest ionisation potential?
- (a)
\([Ne]3s^2, 3p^2\)
- (b)
\([Ne]3s^2, 3p^3\)
- (c)
\([Ne]3s^2, 3p^1\)
- (d)
\([Ar]3d^{10}, 4s^2,4p^3\)
Due to extra stable half-filled electronic configuration.
The correct order of increasing value of electron gain enthalpy among the following is
- (a)
O < S < F < Cl
- (b)
O < S < Cl < F
- (c)
S < O < F < Cl
- (d)
S < O < Cl < F
Irregular variation in case of period 2 is only due to small size of F and O which causes electron-electron repulsion to extra added electron.
Which of the following has lowest electronegativity?
- (a)
N
- (b)
F
- (c)
Na
- (d)
K
Due to largest size among N,F, Na and K.
Which is the most reactive among following?
- (a)
Na
- (b)
K
- (c)
Cs
- (d)
Mg
All are metals but Cs is most electropositive.
Considering the elements B,C,N,F and Si, the correct order of their non-metallic character is
- (a)
B > C > Si > N >F
- (b)
Si > C > B > N > F
- (c)
F > N > C > B > Si
- (d)
F > N > C > Si > B
More the electronegative atom, greater will be their non-metallic character.
Considering the elements B, Al, Mg and K, the correct order of their metallic character is
- (a)
B > Al > Mg > K
- (b)
Al > Mg > B > K
- (c)
Mg > Al > K > B
- (d)
K > Mg > Al > B
More the value of electropositivity, greater will be its metallic character.
Which of the following is incorrect?
- (a)
Mendeleef was first to publish periodic law
- (b)
Mendeleef used the atomic mass of element to observe the periodicity
- (c)
Dobereiner was first to initiate the study of periodic relationship
- (d)
Lother Meyer has plotted a graph between atomic mass and properties of element
Lother Meyer has plotted a graph between atomic mass and properties of element.
Incorrect statement for periodic classification of element is
- (a)
The properties of elements are periodic function of their atomic numbers
- (b)
Non-metallic elements are less in number than metallic elements
- (c)
For transition elements, the 3d-orbitals are filled with electrons after 3p-orbitals and before 4s-orbital
- (d)
The first ionisation enthalpies of elements generally increase with increase in atomic number as we go along a period.
3d-orbital of transition element is filled after 4s-orbital due to less energy value of 4s than 3d
4s1, 3d10, 3d5 are the valence shell electronic configuration of ....... respectively.
- (a)
K, Ca, Cr
- (b)
K, Ca, Cu
- (c)
K, Cu, Cr
- (d)
Cu, Zn, Cr
Valence shell
19K = [Ar]4s1 4s1
29Cu = [Ar]4s1, 3d10 3d10
24Cr = [Ar]4s1, 3d5 3d5
For which of the following the second IE is lower than first IE?
- (a)
Mg
- (b)
Ne
- (c)
C
- (d)
None of these
IE1 of Ne is greater because of inert gas electronic configuration
Which of the following requires least energy to show photoelectric effect?
- (a)
Cs
- (b)
Na
- (c)
Mg
- (d)
Cl
Because Cs have least value of IE.
Which of the element show positive as well as negative oxidation state among the following?
- (a)
O
- (b)
Na
- (c)
F
- (d)
K
O has positive oxidation state in OF2 while exists in negative oxidation state in H2O.
Match the following and choose the correct option.
Column I | Column II |
---|---|
A.Al3+ < Mg2+ < Na+ < F- B. B < C < N \(\ge\)O C. I < Br < F < Cl D. Li < Na < K < Rb |
p.IE1 q. Ionic size r. Metallic radius s.Electron gain enthalpy |
- (a)
A B C D p q s r - (b)
A B C D q s p r - (c)
A B C D q p s r - (d)
A B C D r s p q
\(IE_1\rightarrow B<C<N\ge O.\)
Ionic size \(\rightarrow Al^{3+}< Mg^{2+}< Na^+<F^-\)
Metallic radius \(\rightarrow\)Li<Na<K<Rb
Electron gain enthalpy\(\rightarrow\)I<Br<F<Cl
The first ionisation potential of Na is 5.1eV. The value of electron gain enthalpy of Na+ will be
- (a)
-2.55 eV
- (b)
-5.1 eV
- (c)
-10.2 eV
- (d)
+2.55 eV
Na \(\longrightarrow\) Na+ + e-, IE1
Na+ + e- \(\longrightarrow\) Na
Electron gain enthalpy of Na+
Because reaction id reverse so
\(\Delta\)Heg = -5.1eV
The correct order of electron gain enthalpy with negative sign of F,Cl,Br and I, having atomic number 9,17,35 and 53 respectively, is
- (a)
I > Br > Cl >F
- (b)
F > Cl > Br > I
- (c)
Cl > F >Br > I
- (d)
Br > Cl > I > F
As we move from top to bottom, size increases but the force of attraction for the added extra electron decreases, thus electron gain enthalpy decreases.
The order should be F > Cl > Br > I
but actual order is Cl > F > Br > I because extra e- added to 2p-orbital of F is repelled to a greater extent than 3p-orbital of Cl-atom hence, Cl has more electron affinity than F.
The set representing the correct order of ionic radius is
- (a)
Li+ > Be2+ >Na+ > Mg2+
- (b)
Na+ > Li+ > Mg2+ > Be2+
- (c)
Li2+ > Na+ > Mg2+ > Be2+
- (d)
Mg2+ > Be2+ > Li+ > Na+
Since, ionic radius decreases from left to right and increases along group.
Na+ > Li+ > Mg2+ > Be2+
The charge/size ratio of a cation determines its polarising power. Which one of the following sequences represents the increasing order of the polarising power of the cationic species, K+, Ca2+, Mg2+, Be2+?
- (a)
Mg2+< Be2+<K+<Ca2+
- (b)
Be2+<K+<Ca2+<Mg2+
- (c)
K+<Ca2+<Mg2+<Be2+
- (d)
Ca2+<Mg2+<Be2+<K+
As \(e\over r\) ratio increases, polarising power increases.
Which one of the following set of cations represents a collection of isoelectronic species?
- (a)
K+, Cl-, Ca2+, Sc3+
- (b)
Ba2+, Sr2+, K+, S2-
- (c)
N3-, O2-,F-,S2-
- (d)
Li+,Na+,Mg2+,Ca2+
The species having same number of electrons are known as isoelectronic species.
Electronic configurations of four elements A,B,C and D are given below
- (a)
1S2,2S2,2p6
- (b)
1s2,2s2,2p4
- (c)
1s2,2s2,2p6,3s1
- (d)
1s2,2s2,2p5
np5 and ns1 elements possess a large tendency to accept the electron than fully and half-filled elements.
Anything that influences the valence electrons will affect the chemistry of the element. Which one of the following factors does not affect the valence shell?
- (a)
Valence principal quantum number (n)
- (b)
Nuclear charge (Z)
- (c)
Nuclear mass
- (d)
Number of core electrons
Nuclear mass (proton +neutron) does not affect the valence shell. It only affects the nuclear charge which affect the valence shell
Which of the following is incorrect statement ?
- (a)
Greater the value of nuclear charge, greater will be the electron gain enthalpy
- (b)
N has nearly to zero \(\Delta_{eg}H\)
- (c)
Electron gain enthalpy decreases from F to I
- (d)
Cl has highest electron gain enthalpy
The real trend for electron gain enthalpy is Cl>F>Br>I