p-Block Elements · JEE Main previous year questions

White Phosphorus on reaction with concentrated $\mathrm{NaOH}$ solution in an inert atmosphere of $\mathrm{C}{\mathrm{O}}_2$ gives phosphine and compound (X). (X) on acidification with $\mathrm{HCl}$ gives compound (Y). The basicity of compound (Y) is :

1. A.2
2. B.4
3. C.1
4. D.3

The electron gain enthalpy (in kJ/mol) of fluorine, chlorine, bromine and iodine, respectively are:

1. A.-296, -325, -333 and -349
2. B.-349, -333, -325 and -296
3. C.-333, -349, -325 and -296
4. D.-333, -325, -349 and -296

The oxoacid of sulphur that does not contain bond between sulphur atoms is

1. A.${\mathrm{H}}_2{\mathrm{S}}_2{\mathrm{O}}_7$
2. B.${\mathrm{H}}_2{\mathrm{S}}_2{\mathrm{O}}_3$
3. C.${\mathrm{H}}_2{\mathrm{S}}_4{\mathrm{O}}_6$
4. D.${\mathrm{H}}_2{\mathrm{S}}_2{\mathrm{O}}_4$

The noble gas that does not occur in the atmosphere is :

1. A.Ne
2. B.He
3. C.Kr
4. D.Rn

The number of pentagons in ${\mathrm{C}}_{60}$ and trigons (triangles) in white phosphorus, respectively, are :

1. A.12 and 3
2. B.20 and 3
3. C.20 and 4
4. D.12 and 4

${\mathrm{C}}_{60}$ an allotrope of carbon contains :

1. A.12 hexagons and 20 pentagons.
2. B.20 hexagons and 12 pentagons.
3. C.16 hexagons and 16 pentagons
4. D.18 hexagons and 14 pentagons.

The correct statements among I to III regarding group 13 element oxides are, (I) Boron trioxide is acidic. (II) Oxides of aluminium and gallium are amphoteric. (III) Oxides of indium and thallium are basic.

1. A.(II) and (III) only
2. B.(I), (II) and (III)
3. C.(I) and (III) only
4. D.(I) and (II) only

1. A.
2. B.
3. C.
4. D.

The upper stratosphere consisting of the ozone layer protects us from sun's radiation that falls in the wavelength region of -

1. A.200-315 nm
2. B.400-550 nm
3. C.0.8-1.5 nm
4. D.600-750 nm

Among the oxides of nitrogen : ${\mathrm{N}}_2{\mathrm{O}}_3$, ${\mathrm{N}}_2{\mathrm{O}}_4$ and ${\mathrm{N}}_2{\mathrm{O}}_5$; the molecule(s) having nitrogen-nitrogen bond is / are :

1. A.Only ${\mathrm{N}}_2{\mathrm{O}}_5$
2. B.${\mathrm{N}}_2{\mathrm{O}}_3$ and ${\mathrm{N}}_2{\mathrm{O}}_5$
3. C.${\mathrm{N}}_2{\mathrm{O}}_4$ and ${\mathrm{N}}_2{\mathrm{O}}_5$
4. D.${\mathrm{N}}_2{\mathrm{O}}_3$ and ${\mathrm{N}}_2{\mathrm{O}}_4$

A sample of $NaCl{O}_3$ is converted by heat to $NaCl$ with a loss of $0.16g$ of oxygen. The residue is dissolved in water and precipitated as $AgCl$. The mass of $AgCl$ (in $g$) obtained will be : (Given : Molar mass of $AgCl=143.5gmo{l}^{-1}$)

1. A.0.35
2. B.0.41
3. C.0.48
4. D.0.54

1. A.
2. B.
3. C.
4. D.

How long (approximate) should water be electrolysed by passing through 100 amperes current so that the oxygen released can completely burn 27.66 g of diborane? (Atomic weight of B = 10.8 u)

1. A.1.6 hours
2. B.6.4 hours
3. C.0.8 hours
4. D.3.2 hours

The compound that does not produce nitrogen gas by the thermal decomposition is :

1. A.$({\text{NH}}_4{)}_2{\text{SO}}_4$
2. B.$\text{Ba}({\text{N}}_3{)}_2$
3. C.$({\text{NH}}_4{)}_2{\text{Cr}}_2{\text{O}}_7$
4. D.${\text{NH}}_4{\text{NO}}_2$

1. A.
2. B.
3. C.
4. D.

At 300 K, the density of a certain gaseous molecule at 2 bar is double to that of dinitrogen (${\mathrm{N}}_2$ ) at 4 bar. The molar mass of gaseous molecule is :

1. A.$28\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$
2. B.$56\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$
3. C.$112\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$
4. D.$224\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$

A metal ‘M’ reacts with nitrogen gas to afford ‘${\mathrm{M}}_3\mathrm{N}$’. ‘${\mathrm{M}}_3\mathrm{N}$’ on heating at high temperature gives back ‘M’ and on reaction with water produces a gas ‘B’. Gas ‘B’ reacts with aqueous solution of $\mathrm{CuS}{\mathrm{O}}_4$ to form a deep blue compound. ‘M’ and ‘B’ respectively are :

1. A.$\mathrm{Li}$ and $\mathrm{N}{\mathrm{H}}_3$
2. B.$\mathrm{Ba}$ and ${\mathrm{N}}_2$
3. C.$\mathrm{Na}$ and $\mathrm{N}{\mathrm{H}}_3$
4. D.$\mathrm{Al}$ and ${\mathrm{N}}_2$

The reaction of zinc with dilute and concentrated nitric acid, respectively, produces :

1. A.$\mathrm{N}{\mathrm{O}}_2$ and $\mathrm{NO}$
2. B.$\mathrm{NO}$ and ${\mathrm{N}}_2\mathrm{O}$
3. C.$\mathrm{N}{\mathrm{O}}_2$ and ${\mathrm{N}}_2\mathrm{O}$
4. D.${\mathrm{N}}_2\mathrm{O}$ and $\mathrm{N}{\mathrm{O}}_2$

In Carius method of estimation of halogens, 250 mg of an organic compound gave 141 mg of AgBr. The percentage of bromine in the compound is: (at. Mass Ag = 108; Br = 80)

1. A.48
2. B.60
3. C.36
4. D.24

Assertion : Nitrogen and Oxygen are the main components in the atmosphere but these do not react to form oxides of nitrogen. Reason : The reaction between nitrogen and oxygen requires high temperature.

1. A.Both assertion and reason are correct, and the reason is the correct explanation for the assertion
2. B.Both assertion and reason are correct, but the reason is not the correct explanation for the assertion
3. C.The assertion is incorrect, but the reason is correct
4. D.Both the assertion and reason are incorrect

The ratio of masses of oxygen and nitrogen in a particular gaseous mixture is 1 : 4. The ratio of number of their molecules is:

1. A.1: 8
2. B.3 : 16
3. C.1 : 4
4. D.7 : 32

Which one of the following depletes ozone layer?

1. A.$\mathrm{CO}$
2. B.$\mathrm{NO}$ and freons
3. C.$\mathrm{S}{\mathrm{O}}_2$
4. D.$\mathrm{C}{\mathrm{O}}_2$

A metal $M$ on heating in nitrogen gas gives $Y$. $Y$ on treatment with ${\mathrm{H}}_2\mathrm{O}$ gives a colourless gas which when passed through $\mathrm{CuS}{\mathrm{O}}_4$ solution gives a blue colour. $Y$ is

1. A.$\mathrm{N}{\mathrm{H}}_3$
2. B.$\mathrm{Mg}(\mathrm{N}{\mathrm{O}}_3{)}_2$
3. C.$\mathrm{M}{\mathrm{g}}_3{\mathrm{N}}_2$
4. D.$\mathrm{MgO}$

The ratio of number of oxygen atoms (O) in 16.0 g ozone (${\mathrm{O}}_3$), 28.0 g carbon monoxide (CO) and 16.0 g oxygen (${\mathrm{O}}_2$) is (Atomic mass : C = 12, O = 16 and Avogadro's constant ${\mathrm{N}}_{\mathrm{A}}=6.0\times 10^{23}\mathrm{mo}{\mathrm{l}}^{-1}$)

1. A.3 : 1 : 2
2. B.1 : 1 : 2
3. C.3 : 1 : 1
4. D.1 : 1 : 1

Copper wire test for halogens is known as

1. A.Dumas' Test
2. B.Beilstein's Test
3. C.Liebig's Test
4. D.Lassaigne's Test