Periodic Table & Periodicity — Page 15 | JEE Chemistry

Q141

The metal mainly used in devising photoelectric cells is :

A Na

B Rb

C Li

D Cs

Correct Answer

Option D

Solution

Cs has least work function value because of less electronegativity thats why it is used in photoelectric cells.

Q142

Given below are two statements : Statement I : Both CaCl2 . 6H2O and MgCl2 . 8H2O undergo dehydration on heating. Statement II : BeO is amphoteric whereas the oxides of other elements in the same group are acidic. In the light of the above statements, choose the correct answer from the options given below :

A Both statement I and statement II are false

B Statement I is false but statement II is true

C Statement I is true but statement II is false

D Both statement I and statement II are true

Correct Answer

Option A

Solution

CaCl2.6H2O

\overset{\Delta}\longrightarrow

CaCl2 + 6H2O MgCl2.6H2O

\overset{\Delta}\longrightarrow

MgCl(OH) + H2O Among alkaline earth metal BeO is amphoteric & rest are basic oxide

Q143

The correct order of conductivity of ions in water is :

A K+ > Na+ > Cs+ > Rb+

B Cs+ > Rb+ > K+ > Na+

C Na+ > K+ > Rb+ > Cs+

D Rb+ > Na+ > K+ > Li+

Correct Answer

Option B

Solution

As the size of gaseous ion decreases, it get more hydrated in water and hence, the size of aqueous ion increases.

When this bulky ion move in solution, it experience greater resistance and hence lower conductivity.

Q144

The set of elements that differ in mutual relationship from those of the other sets is :

A Li - Na

B Be - Al

C B - Si

D Li - Mg

Correct Answer

Option A

Solution

Li–Mg, B–Si, Be–Al show diagonal relationship but Li and Na do not show diagonal relationship as both belongs to same group and not placed diagonally.

Q145

One of the by-products formed during the recovery of NH3 from Solvay process is :

A Ca(OH)2

B NH4Cl

C NaHCO3

D CaCl2

Correct Answer

Option D

Solution

Recovery of NH3 :

2N{H_4}Cl + Ca{\left( {OH} \right)_2} \to 2N{H_3} + CaC{l_2} + {H_2}O

By product : CaCl2

Q146

Match with

List - I		List - II
(a)	$Ca{(OCl)_2}$	(i)	Antacid
(b)	$CaS{O_4}.{1 \over 2}{H_2}O$	(ii)	Cement
(c)	$CaO$	(iii)	Bleach
(d)	$CaC{O_3}$	(iv)	Plaster of paris Choose the most appropriate answer from the options given below :

A (a) - (i), (b) - (iv), (c) - (iii), (d) - (ii)

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

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

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

Correct Answer

Option C

Solution

CaSO4

{1 \over 2}

H2O - Plaster of Paris Ca(OCl)2 - Bleaching agent CaO is used in cement CaCO3 is used as an Antacid

Q147

Match with :

List - I		List - II
(a)	Be	(i)	treatment of cancer
(b)	Mg	(ii)	extraction of metals
(c)	Ca	(iii)	incendiary bombs and signals
(d)	Ra	(iv)	windows of X-ray tubes
()		(v)	bearings for motor engines Choose the most appropriate answer from the option given below :

A (a)-(iv), (b)-(iii), (c)-(i), (d)-(ii)

B (a)-(iii), (b)-(iv), (c)-(v), (d)-(ii)

C (a)-(iii), (b)-(iv), (c)-(ii), (d)-(v)

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

Correct Answer

Option D

Solution

Beryllium is used in the manufacture of alloys.

Metallic beryllium is used for making windows of X-ray tubes.

Radium salts are used in radiotherapy, for example, in the treatment of cancer.

Magnesium (powder and ribbon) is used in flash powders and bulbs, incendiary bombs and signals.

Calcium is used in the extraction of metals from oxides which are difficult to reduce with carbon.

Q148

The set in which compounds have different nature is :

A B(OH)3 and H3PO3

B B(OH)3 and Al(OH)3

C NaOH and Ca(OH)2

D Be(OH)2 and Al(OH)3

Correct Answer

Option B

Solution

(A) Both are acidic in nature.

B(OH)3 is orthoboric acid.

It can accept a pair of electrons from Lewis bases and hence, act as Lewis acid.

H3PO3 is (phosphorus acid) diprotic acid as it readily ionises two protons.

(B) B(OH)3 is acidic and Al(OH)3 is amphoteric in nature.

(C) Both NaOH and Ca(OH)2 are basic hydroxides.

(D) Both Be(OH)2 and Al(OH)3 are amphoteric hydroxides.

Hence, only B(OH)3 and Al(OH)3 have different nature.

Q149

Match with (Elements) (Properties)

List - I		List - II
(a)	Ba	(i)	Organic solvent soluble compounds
(b)	Ca	(ii)	Outer electronic configuration $6{s^2}$
(c)	Li	(iii)	Oxalate insoluble in water
(d)	Na	(iv)	Formation of very strong monoacidic base

A (a)-(ii), (b)-(iii), (c)-(i) and (d)-(iv)

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

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

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

Correct Answer

Option A

Solution

(a) 'Ba' having outer electronic configuration 6s2 (b) CaC2O4 is water insoluble (c) 'Li' is soluble in organic solvents (d) NaOH is strong Monoacidic base among given

Q150

Given below are two statements : One is labelled as Assertion A and the other labelled as Reason R. Assertion A : Lithium halides are some what covalent in nature. Reason R : Lithium posses high polarisation capability. In the light of the above statements, choose the most appropriate answer from the options given below :

A A is true but R is false

B A is false but R is true

C Both A and R are true but R is NOT the correct explanation of A

D Both A and R are true and R is the correct explanation of A

Correct Answer

Option D

Solution

Lithium due to small size has very high polarization capability and thus increases covalent nature of Halides.