Periodic Table & Periodicity — Page 7 | JEE Chemistry

Q61

Match with . Electronic configuration ${\Delta _i}H$ in kJ $mo{l^{ - 1}}$

List - I		List - II
(a)	$1{s^2}2{s^2}$	(i)	801
(b)	$1{s^2}2{s^2}2{p^4}$	(ii)	899
(c)	$1{s^2}2{s^2}2{p^3}$	(iii)	1314
(d)	$1{s^2}2{s^2}2{p^1}$	(iv)	1402 Choose the most appropriate answer from the options given below :

A (a)

\to

(i), (b)

\to

(iii), (c)

\to

(iv), (d)

\to

(iii)

B (a)

\to

(iv), (b)

\to

(i), (c)

\to

(ii), (d)

\to

(iii)

C (a)

\to

(ii), (b)

\to

(iii), (c)

\to

(iv), (d)

\to

(i)

D (a)

\to

(i), (b)

\to

(iv), (c)

\to

(iii), (d)

\to

(ii)

Correct Answer

Option C

Solution

(a) 1s2 2s2 $\to$ Be (b) 1s2 2s2 2p4 $\to$ O (c) 1s2 2s2 2p3 $\to$ N (d) 1s2 2s2 2p1 $\to$ B The ionization enthalpy order is B < Be < O < N Be has more IE compared to B due to extra stability & N has more IE compared to oxygen due to extra stability.

Hence, N $\to$ 1402 kJ/mol O $\to$ 1314 kJ/mol B $\to$ 801 kJ/mol Be $\to$ 899 kJ/mol

Q62

The characteristics of elements X, Y and Z with atomic numbers, respectively, 33, 53 and 83 are :

A X and Y are metalloids and Z is a metal.

B X and Z are non-metals and Y is a metalloid.

C X is a metalloid, Y is a non-metal and Z is a metal.

D X, Y and Z are metals.

Correct Answer

Option C

Solution

X(Z = 33) = As (metalloid) Y(Z = 53) = I (non-metal) Z(Z = 83) = Bi (metal)

Q63

The first ionization energy of magnesium is smaller as compared to that of elements X and Y, but higher than that of Z. The elements X, Y and Z, respectively, are :

A neon, sodium and chlorine

B argon, chlorine and sodium

C chlorine, lithium and sodium

D argon, lithium and sodium

Correct Answer

Option B

Solution

We are told: $\mathrm{IE}(\mathrm{Mg})$ is smaller than $\mathrm{IE}(X)$ and $\mathrm{IE}(Y)$ . $\mathrm{IE}(\mathrm{Mg})$ is greater than $\mathrm{IE}(Z)$ .

Hence we want: $\mathrm{IE}(\mathrm{Mg}) \mathrm{IE}(Z).$ Approximate first ionization energies (in $\mathrm{kJ\,mol^{-1}}$ ) of the relevant elements: $\mathrm{IE}(\mathrm{Ne}) \approx 2080$ $\mathrm{IE}(\mathrm{Na}) \approx 496$ $\mathrm{IE}(\mathrm{Mg}) \approx 738$ $\mathrm{IE}(\mathrm{Al}) \approx 578$ (not listed but for reference) $\mathrm{IE}(\mathrm{Si}) \approx 787$ (not listed but for reference) $\mathrm{IE}(\mathrm{P}) \approx 1012$ (not listed but for reference) $\mathrm{IE}(\mathrm{S}) \approx 1000$ (not listed but for reference) $\mathrm{IE}(\mathrm{Cl}) \approx 1251$ $\mathrm{IE}(\mathrm{Ar}) \approx 1521$ $\mathrm{IE}(\mathrm{Li}) \approx 520$ We test each option: (A) neon, sodium, chlorine $X=\mathrm{Ne}$ : $\mathrm{IE}(\mathrm{Ne})=2080 > 738$ ✓ $Y=\mathrm{Na}$ : $\mathrm{IE}(\mathrm{Na})=496$ Z=\mathrm{Cl} $:$ \mathrm{IE}(\mathrm{Cl})=1251 > 738 $✗ (contradicts “$ \mathrm{Mg} $>$ Z $”) So (A) does not fit the requirement. (B) argon, chlorine, sodium$ X=\mathrm{Ar} $:$ \mathrm{IE}(\mathrm{Ar})=1521 > 738 $✓$ Y=\mathrm{Cl} $:$ \mathrm{IE}(\mathrm{Cl})=1251 > 738 $✓$ Z=\mathrm{Na} $:$ \mathrm{IE}(\mathrm{Na})=496 Thus $\mathrm{IE}(\mathrm{Mg}) \mathrm{IE}(\mathrm{Na})$ .

This matches perfectly.

(C) chlorine, lithium, sodium $X=\mathrm{Cl}$ : $\mathrm{IE}(\mathrm{Cl})=1251 > 738$ ✓ $Y=\mathrm{Li}$ : $\mathrm{IE}(\mathrm{Li})=520$ Z=\mathrm{Na} $:$ \mathrm{IE}(\mathrm{Na})=496 (D) argon, lithium, sodium $X=\mathrm{Ar}$ : $\mathrm{IE}(\mathrm{Ar})=1521 > 738$ ✓ $Y=\mathrm{Li}$ : $\mathrm{IE}(\mathrm{Li})=520$ Z=\mathrm{Na} $:$ \mathrm{IE}(\mathrm{Na})=496 Hence only (B) satisfies all conditions: $\boxed{\text{(B) argon, chlorine, and sodium.}}$

Q64

Which one of the following statements for D.I. Mendeleeff, is incorrect?

A He authored the textbook - Principles of Chemistry

B At the time, he proposed Periodic Table of elements structure of atom was known.

C Element with atomic number 101 is named after him.

D He invented accurate barometer.

Correct Answer

Option B

Solution

In 1869, the Russian chemist Dmitri Mendeleev came to prominence with his tabular diagram of known elements, but basic atomic structure the idea that everything is made of atoms was pioneered by John Dalton (1766-1844) in a book he published in 1808.

Q65

The ionic radii of K+, Na+, Al3+ and Mg2+ are in the order:

A Na+ < K+ < Mg2+ < Al3+

B Al3+ < Mg2+ < K+ < Na+

C Al3+ < Mg2+ < Na+ < K+

D K+ < Al3+ < Mg2+ < Na+

Correct Answer

Option C

Solution

Al3+, Mg2+ and Na+ are isoelectronic ionic species.

For monoatomic ionic isoelectronic species as positive charge increases ionic size decreases.

The order of size of Na+ & K+ is Na+ < K+ $\therefore$ Order of ionic radii is : Al3+ < Mg2+ < Na+ < K+

Q66

The ionic radii of F

-

and O2

-

respectively are 1.33

\mathop A\limits^o

and 1.4

\mathop A\limits^o

, while the covalent radius of N is 0.74

\mathop A\limits^o

. The correct statement for the ionic radius of N3

-

from the following is :

A It is smaller than F

-

and N

B It is bigger than O2

-

and F

-

C It is bigger than F

-

and N, but smaller than of O2

-

D It is smaller than O2

-

and F

-

, but bigger than of N

Correct Answer

Option B

Solution

F $-$ , O2 $-$ and N3 $-$ all are isoelectronic species in which N3 $-$ have least number of protons due to which it's size increases as least nuclear attraction is experienced by the outer shell electrons.

Size order N3 $-$ > O2 $-$ > F $-$

Q67

Match with :

List - I		List - II
(a)	NaOH	(i)	Acidic
(b)	$Be{(OH)_2}$	(ii)	Basic
(c)	$Ca{(OH)_2}$	(iii)	Amphoteric
(d)	$B{(OH)_3}$ (e) $Al{(OH)_3}$ Choose the most appropriate answer from the options given below	()

A (a)-(ii), (b)-(ii), (c)-(iii), (d)-(ii), (e)-(iii)

B (a)-(ii), (b)-(iii), (c)-(ii), (d)-(i), (e)-(iii)

C (a)-(ii), (b)-(ii), (c)-(iii), (d)-(i), (e)-(iii)

D (a)-(ii), (b)-(i), (c)-(ii), (d)-(iii), (e)-(iii)

Correct Answer

Option B

Solution

NaOH $\to$ Basic Be(OH)2 $\to$ Amphoteric Ca(OH)2 $\to$ Basic B(OH)3 $\to$ Acidic Al(OH)3 $\to$ Amphoteric

Q68

The correct order of first ionisation enthalpy is :

A Mg < S < Al < P

B Mg < Al < S < P

C Al < Mg < S < P

D Mg < Al < P < S

Correct Answer

Option C

Solution

\begin{array}{lll}{Mg} & {Al} & P & {S \to IE} \end{array}

order $\Rightarrow$ Al < Mg < S < P Valence [Ne] :

\begin{array}{lll}{\mathop {3{s^2}}\limits^{Mg} } & {\mathop {3{s^2}3{P^1}}\limits^{Al} } & {\mathop {3{s^2}3{P^3}}\limits^P } & {\mathop {3{s^2}3{P^4}}\limits^S } \end{array}

Q69

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Barium carbonate is insoluble in water and is highly stable. Reason (R) : The thermal stability of the carbonates increases with increasing cationic size.

A Both (A) and (R) are true and (R) is the true explanation of (A)

B (A) is true but (R) is false

C Both (A) and (R) are true but (R) is not the true explanation of (A)

D (A) is false but (R) is true.

Correct Answer

Option A

Solution

In IIA group on moving down the group size of cation increases and show thermal stability of carbonate increases.

Q70

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Metallic character decreases and non-metallic character increases on moving from left to right in a period. Reason (R) : It is due to increase in ionisation enthalpy and decrease in electron gain enthalpy, when one moves from left to right in a period. In the light of the above statements, choose the most appropriate answer from the options given below :

A (A) is false but (R) is true.

B (A) is true but (R) is false

C Both (A) and (R) are correct and (R) is the correct explanation of (A)

D Both (A) and (R) are correct but (R) is not the correct explanation of (A)

Correct Answer

Option B

Solution

From left to right in periodic table :- Metallic character decreases Non-metallic character increases $\Rightarrow$ It is due to increase in ionization enthalpy and increase in electron gain enthalpy.