Practice Start Test

Periodic Table & Periodicity

NEET Chemistry · 94 questions · Page 3 of 10 · Click an option or "Show Solution" to reveal answer

Q21
Identify the wrong statement in the following.
A Amongst isoelectronic species, smaller the positive charge on the cation, smaller is the ionic radius.
B Amongst isoelectronic species, greater the negative charge on the anion, larger is the ionic radius.
C Atomic radius of the elements increases as one moves down the first group of the periodic table.
D Atomic radius of the elements decreases as one moves across from left to right in the 2 nd period of the periodic table.
Correct Answer
Option A
Solution

When positive charge on the cation increases, effective nuclear charge increases. Thus atomic size decreases.

Q22
What is the value of electron gain enthalpy of Na + if IE 1 of Na = 5.1 eV?
A −- 5.1 eV
B −- 10.2 eV
C +2.55 eV
D +10.2 eV
Correct Answer
Option A
Solution

Na →\to Na + + e - ;

Δ\Delta

H = 5.1 eV Na + + e - →\to Na;

Δ\Delta

H = -5.1 eV

Q23
Among the following which one has the highest cation to anion size ratio ?
A CsI
B CsF
C LiF
D NaF
Correct Answer
Option B
Solution

The ratio in cation and anion size will be maximum when the cation is largest size and the anion is smallest size.

So among the given species, Cs + has maximum size among given cations and F - has smallest size among the given anions, So Cs/F has highest r c /r a

Q24
Among the elements Ca, Mg, P and Cl, the order of increasing atomic radii is
A Mg < Ca < Cl < P
B Cl < P < Mg < Ca
C P < Cl < Ca < Mg
D Ca < Mg < P < Cl
Correct Answer
Option B
Solution

Atomic radius decreases on moving from left to right in a period. so order of sizes for Cl, P and Mg is Cl < P < Mg.

Down the group size increases.

So overall order is : Cl < P < Mg < Ca.

Q25
The correct order of the decreasing ionic radii among the following isoelectronic species is
A Ca 2+ > K + > S 2−- > Cll −-
B Cll −- > S 2−- > Ca 2+ > K +
C S 2−- > Cl −- > K + > Ca 2+
D K + > Ca 2+ > Cl −- > S 2−-
Correct Answer
Option C
Solution

For isoelectronic species, ionic radius increases when there is increase in negative charge.

It happens because effective nuclear charge on the atom (Z eff ) decreases.

Same when ionic radius decreases with increase in positive charge as Z eff increases.

Q26
Which of the following represents the correct order of increasing electron gain enthalpy with negative sign for the elements O, S, F and Cll ?
A Cll < F < O < S
B O < S < F < Cll
C F < S < O < Cll
D S < O < Cll < F
Correct Answer
Option B
Solution

Cl atom has the highest electron affinity in the periodic table.

F is a member of group 17 has highest electron gain enthalpy than S which is a group 16 element.

This is turn is higher than the electron affinity of O atom.

Thus, Cl > F > S > O

Q27
Amongst the elements with following electronic configurations, which one of them may have the highest ionisation energy ?
A Ne [3s 2 3p 2 ]
B Ar [3d 10 4s 2 4p 3 ]
C Ne [3s 2 3p 1 ]
D Ne [3s 2 3p 3 ]
Correct Answer
Option D
Solution

Among the given options (a), (c) and (d), the option (d) has the highest ionisation energy because of extra stability associated with half-filled 3p-orbital.

In option (b), the presence of 3d 10 electrons offers shielding effect, as a result the 4p 3 electrons do not experience much nuclear charge and hence the electrons can be removed easily.

Q28
With which of the following electronic configuration an atom has the lowest ionisation enthalpy ?
A 1s 2 2s 2 2p 3
B 1s 2 2s 2 2p 5 3s 1
C 1s 2 2s 2 2p 6
D 1s 2 2s 2 2p 5
Correct Answer
Option B
Solution

The larger the atomic size, smaller is the value of the ionisation enthalpy.

Again higher the screening effect, lesser is the value of ionisation potential, So option(b) has lowest ionisation enthalpy.

Q29
Which one of the following ionic species has the greatest proton affinity to form stable compound ?
A NH2−_2^ -
B F −-
C I −-
D HS −-
Correct Answer
Option A
Solution

Going from left to right across a period in the periodic table, the basicity decreases as the electronegativity of the atom possessing the lone pair of electron increases.

Hence basicity of

NH2−NH_2^-

is higher than F - .

In moving down a group, as the atomic mass increases, basicity decreases.

Hence F - is more basic than I - and HO - is more basic than HS-.

Hence among the ionic species,

NH2−NH_2^-

has maximum proton affinity.

Q30
Identify the correct order of the size of the following :
A Ca 2+ < K + < Ar < Cl −- < S 2−-
B Ar < Ca 2+ < K + < Cl −- < S 2−-
C Ca 2+ < Ar < K + < Cl −- < S 2−-
D Ca 2+ < K + < Ar < S 2−- < Cl −-
Correct Answer
Option A
Solution

Among isoelectronic ions, ionic radius of anions is more than that of cations.

Further size of the anion increases with increase in negative charge and size of the cation decreases with increase in positive charge.

Ready for a full NEET mock test? Timed · full syllabus · instant results
Take a Mock Test →