Question 1

Which of the following arrangements shows the decreasing order of acidic nature?

Accepted Answer

N2O5 > SO3 > CO2 > CO. The correct option reflects the trend in acidic strength based on the oxides' ability to donate protons; N2O5 is a strong acid due to its high oxidation state and ability to form strong acids in solution, followed by SO3, which is also a strong acid, while CO2 and CO are weaker due to their lower oxidation states and less acidic behavior.

Question 2

Which one of the following oxides shows amphoteric behaviour?

Accepted Answer

SnO₂. SnO2 (Sn4+) is amphoteric, reacting with both acids and bases. SiO2 and CO2 are acidic and CaO is basic, so the amphoteric oxide is SnO2, not SiO2.

Question 3

In boric acid (H₃BO₃), the hybridization states of the boron atom and the oxygen atoms are, respectively,

Accepted Answer

sp² and sp³. In boric acid, the boron atom is bonded to three oxygen atoms through single bonds and has a trigonal planar geometry, indicating sp² hybridization. The oxygen atoms, which are involved in both single bonds and a lone pair, adopt a bent shape, leading to sp³ hybridization.

Question 4

A xenon fluoride compound contains 53.5% xenon by mass. What oxidation state does xenon have in this compound?

Accepted Answer

+6. 131/(131+19n) = 0.535 gives n = 6, so the compound is XeF6 and xenon is +6, not 0.

Question 5

For a cement of good quality, what should be the approximate ratios of the following?
I. Silica to alumina
II. CaO to the combined oxides of SiO2, Al2O3 and Fe2O3

Accepted Answer

I = 2.5 to 4, II = close to 2. The correct option indicates that a good quality cement should have a silica to alumina ratio between 2.5 and 4, which ensures proper strength and durability, while the calcium oxide to the combined oxides ratio being close to 2 supports optimal chemical reactions during hydration.

Question 6

Because the ns² electrons of the valence shell do not readily take part in bonding, which statement is correct?

Accepted Answer

Sn2+ is reducing, whereas Pb4+ is oxidising. Because the inert pair effect stabilises the lower oxidation state down the group, Sn2+ tends to be oxidised (a reducing agent) while Pb4+ tends to be reduced (an oxidising agent). So option 3 is correct.

Question 7

An element from group 14 is oxidized to give its oxide. The oxide is gaseous, and when it is dissolved in water, the pH of the solution falls. On adding more hydroxide of a group 2 metal, a precipitate is formed. Which oxide could this be?

Accepted Answer

CO2. CO2 is gaseous, dissolves to give carbonic acid (pH falls), and forms a CaCO3 precipitate with a group-2 hydroxide. SnO2 is a solid, and CO is neutral, so the oxide is CO2.

Question 8

In silicon dioxide, which statement best describes the bonding arrangement around silicon?

Accepted Answer

Each silicon atom is surrounded by four oxygen atoms, and each oxygen atom is linked to two silicon atoms.. In SiO2 each silicon is bonded to four oxygens and each oxygen bridges two silicons (a 3D tetrahedral network). The stored statement (Si bonded to two O) is wrong.

Question 9

Which of the following statements is correct?

Accepted Answer

In the solid state, the chlorides of both beryllium and aluminium exist with bridged structures.. Beryllium and aluminum chlorides form bridged structures in their solid states due to the presence of dimeric units, which involve bridging chloride ions between metal centers, reflecting their covalent character and coordination chemistry.

Question 10

Choose the statement that is not correct:

Accepted Answer

Hydrolysis of a trialkylchlorosilane produces R3SiOH.. The statement about the hydrolysis of a trialkylchlorosilane producing R3SiOH is incorrect because the hydrolysis of trialkylchlorosilanes typically results in the formation of silanol (R3SiOH) and hydrochloric acid, but the context implies a misunderstanding of the product formation.

Question 11

Carbon, silicon and germanium show catenation in the order Ge < Si < C. Which set gives the bond dissociation energies (in kJ mol−1) for C–C, Si–Si and Ge–Ge bonds, respectively?

Accepted Answer

348, 297, 260. Since catenation decreases Ge Si-Si (297) > Ge-Ge (260) - option 0. The stored order is reversed.

Question 12

Which of the following is an example of a three-dimensional silicate structure?

Accepted Answer

Zeolites. Zeolites are characterized by their three-dimensional framework structure, which consists of interconnected tetrahedra of silicon and aluminum, allowing for unique properties such as ion exchange and molecular sieving.

Question 13

Carbon dioxide and nitrogen do not support combustion. Yet carbon dioxide is chosen over nitrogen for extinguishing fires because carbon dioxide

Accepted Answer

has a greater density than nitrogen. CO2 (M=44) is denser than N2 (M=28), so it settles over the flames and excludes oxygen. It is chosen for its density, not because it is more reactive (it is inert).

Question 14

During roasting of metal sulphides, a gas X is evolved as a by-product. X is a colourless gas with a suffocating smell of burning sulphur, contributes to severe damage to the respiratory system through acid rain, and its aqueous solution is acidic and behaves as a reducing agent. The corre

Accepted Answer

SO2. Gas X is sulfur dioxide (SO2), which is colorless, has a pungent smell reminiscent of burning sulfur, and is known to contribute to acid rain, causing respiratory issues. Its aqueous solution forms sulfurous acid, which is acidic and can act as a reducing agent.

Question 15

Which oxyacid of phosphorus contains phosphorus in its lowest oxidation state?

Accepted Answer

Hypophosphorous acid. In hypophosphorous acid (H3PO2) phosphorus is in the +1 state, lower than +3 (phosphorous acid) and +5 (ortho/pyro/meta phosphoric acids). So hypophosphorous acid has P in its lowest common oxidation state.

Question 16

In a molecule of cyclotrimetaphosphoric acid, what is the count of single bonds and double bonds present?

Accepted Answer

3 double bonds; 9 single bonds. Cyclotrimetaphosphoric acid (HPO3)3 is a 6-membered P-O-P ring of 3 P atoms. Each P carries one terminal P=O double bond (3 double bonds total) and the remaining P-O linkages (6 bridging + 3 to OH) give 9 P-O single bonds. So 3 double and 9 single bonds.

Question 17

Which sulphur-containing compound is used as a refrigerant?

Accepted Answer

SO2. Sulfur dioxide (SO2) is used as a refrigerant due to its favorable thermodynamic properties, which allow it to efficiently absorb and release heat during the refrigeration cycle.

Question 18

Which of the following formulas represents Caro’s acid?

Accepted Answer

H2SO5. Caro's acid is peroxymonosulphuric acid, H2SO5, which contains one peroxy (-O-O-) linkage. (H2S2O8 is peroxydisulphuric/Marshall's acid.)

Question 19

Which of the following acids can produce two distinct series of salts?

Accepted Answer

H3PO3. H3PO3, or phosphorous acid, can donate two protons, allowing it to form two distinct series of salts: one from its diprotic nature and another from its ability to act as a weak acid. This characteristic differentiates it from the other acids listed, which do not exhibit this dual salt formation.

Question 20

Which one of the following ions is not classified as a pseudohalide?

Accepted Answer

RCOO−. RCOO−, or the carboxylate ion, is not classified as a pseudohalide because it does not share the same structural and bonding characteristics typical of pseudohalides, which usually mimic the behavior of halides in chemical reactions.

Question 21

In hypophosphorous acid, how many hydrogen atoms are directly bonded to the phosphorus atom?

Accepted Answer

two. Hypophosphorous acid contains a phosphorus atom that is bonded to two hydrogen atoms and one hydroxyl group, resulting in a total of two hydrogen atoms directly attached to the phosphorus.

Question 22

Which substances are formed when hypochlorous acid undergoes disproportionation?

Accepted Answer

Hydrochloric acid and chloric acid. Disproportionation of hypochlorous acid involves the simultaneous oxidation and reduction of the same species, resulting in the formation of hydrochloric acid (HCl) and chloric acid (HClO3), where chlorine is both oxidized and reduced.

Question 23

Identify the reaction involving a xenon compound that does not occur feasibly.

Accepted Answer

XeO3 + 6HF → XeF6 + 3H2O. XeO3 + 6HF -> XeF6 + 3H2O does not occur; the reverse is favourable since XeF6 is readily hydrolysed by water to XeO3, and weak HF cannot reconvert it. The other three reactions (hydrolysis of XeF4/XeF2, and XeF6 + RbF -> [Rb][XeF7]) are all feasible.

Question 24

Which of the following sequences correctly shows the acids in order of increasing acidity?

Accepted Answer

HOCl < HOClO < HOClO2 < HOClO3. The correct option reflects the increasing acidity of the hypochlorous acid derivatives, where the presence of more oxygen atoms generally increases acidity due to greater electronegativity and stability of the conjugate base.

Question 25

Which of the following nitrogen oxides contain one or more N–N bonds?
(i) N2O
(ii) N2O3
(iii) N2O4
(iv) N2O5

Accepted Answer

(i), (ii) and (iii). N2O, N2O3, and N2O4 all contain N–N bonds due to their molecular structures, where nitrogen atoms are bonded to each other. In contrast, N2O5 does not have an N–N bond, as it consists of nitrogen and oxygen without direct nitrogen-to-nitrogen connections.

Question 26

In biological systems, which element is involved in the oxidation of water to molecular oxygen (O2)?

Accepted Answer

Mn. In photosystem II the oxygen-evolving complex is a manganese (Mn4Ca) cluster that catalyses the oxidation of water to O2. So manganese is the element involved in biological water oxidation.

Question 27

Which of the following substances serves as the base of talcum powder?

Accepted Answer

Magnesium hydrosilicate. Magnesium hydrosilicate is the primary component of talcum powder, providing its soft texture and absorbent properties, making it suitable for personal care products.

Question 28

Which carbide does not produce any hydrocarbon when it reacts with water?

Accepted Answer

SiC. Silicon carbide (SiC) does not produce hydrocarbons when it reacts with water because it does not contain carbon in a form that can form hydrocarbons; instead, it primarily reacts to produce silicon dioxide and hydrogen.

Question 29

In boric acid (H3BO3), what are the hybridization states of the boron atom and the oxygen atoms, respectively?

Accepted Answer

sp2 and sp3. In boric acid, the boron atom is bonded to three oxygen atoms through single bonds, leading to a trigonal planar geometry, which corresponds to sp2 hybridization. The oxygen atoms, which are involved in both single bonds and a hydroxyl group, exhibit sp3 hybridization due to their tetrahedral arrangement.

Question 30

Which one of the following properties is not shown by NO?

Accepted Answer

It is diamagnetic in gaseous state. Nitric oxide (NO) is actually paramagnetic due to the presence of an unpaired electron, which contradicts the property of being diamagnetic. Therefore, this option is incorrect.

Question 31

Which of the following on thermal decomposition yields a basic as well as acidic oxide ?

Accepted Answer

CaCO3. Calcium carbonate (CaCO3) decomposes upon heating to produce calcium oxide (CaO), which is a basic oxide, and carbon dioxide (CO2), which can form carbonic acid in solution, thus yielding both a basic and an acidic oxide.

Question 32

A metal, M forms chlorides in its +2 and +4 oxidation states. Which of the following statements about these chlorides is correct?

Accepted Answer

MCl2 is more ionic than MCl4. A lower oxidation state gives a more ionic (more electropositive) bond, so MCl2 is more ionic than the more covalent MCl4. Hence 'MCl2 is more ionic than MCl4' is the correct statement; MCl4, being covalent, is the more volatile, more easily hydrolysed and more soluble in organic solvents.

Question 33

The stability of dihalides of Si, Ge, Sn and Pb increases steadily in the sequence

Accepted Answer

SiX2 << GeX2 << SnX2 << PbX2. The stability of the dihalides increases with the size of the central atom, as larger atoms like Pb can better accommodate the larger halide ions, leading to more stable compounds. In contrast, smaller atoms like Si form less stable dihalides due to their higher charge density and stronger bond polarization.

Question 34

Which one of the following is the correct statement?

Accepted Answer

Chlorides of both beryllium and aluminium have bridged chloride structures in solid phase. Beryllium and aluminum chlorides form bridged structures in their solid phases due to the presence of covalent bonds and the ability to form dimeric or polymeric arrangements, which is characteristic of their chemistry.

Question 35

Which of the following substituted silanes produces a cross-linked silicone polymer when it undergoes hydrolysis?

Accepted Answer

RSiCl3. RSiCl3 contains one silicon atom bonded to one organic group and three chlorine atoms, allowing it to undergo hydrolysis and form silanol groups. These silanol groups can then react with each other to create a cross-linked silicone polymer structure.

Question 36

In view of the signs of ΔrG° for the following reactions:
PbO2 + Pb → 2PbO, ΔrG° < 0
SnO2 + Sn → 2SnO, ΔrG° > 0
which oxidation states are more characteristics for lead and tin ?

Accepted Answer

For lead +2, for tin +4. The negative ΔrG° for the reaction involving Pb indicates that lead commonly exists in the +2 oxidation state, which is more stable and favorable, while the positive ΔrG° for the Sn reaction suggests that tin is more stable in the +4 oxidation state.

Question 37

When metal ‘M’ is treated with NaOH, a white gelatinous precipitate ‘X’ is obtained, which is soluble in excess of NaOH. Compound ‘X’ when heated strongly gives an oxide which is used in chromatography as an adsorbent. The metal ‘M’ is:

Accepted Answer

Al. Aluminum reacts with sodium hydroxide to form a white gelatinous precipitate of aluminum hydroxide, which is soluble in excess NaOH. Upon heating, aluminum hydroxide decomposes to form aluminum oxide, a substance commonly used as an adsorbent in chromatography.

Question 38

Aluminium is usually found in +3 oxidation state. In contrast, thallium exists in +1 and +3 oxidation states. This is due to:

Accepted Answer

inert pair effect. The inert pair effect explains why heavier elements like thallium exhibit a +1 oxidation state more readily than their lighter counterparts, as the s-electrons become less involved in bonding and remain non-ionized, leading to a preference for the +1 state.

Question 39

C60, an allotrope of carbon contains:

Accepted Answer

20 hexagons and 12 pentagons.. C60, also known as buckminsterfullerene, is structured like a soccer ball, consisting of 20 hexagonal and 12 pentagonal faces, which is characteristic of its spherical geometry and stability.

Question 40

With reference to the Hall–Héroult method used for extracting aluminium, identify the statement that is incorrect.

Accepted Answer

Na3AlF6 acts as the electrolyte. The statement is incorrect because Na3AlF6, also known as cryolite, is not the electrolyte itself; rather, it is used to dissolve alumina (Al2O3) and facilitate the electrolysis process in the Hall–Héroult method.

Question 41

In case of nitrogen, NCl3 is possible but not NCl5 while in case of phosphorus, PCl3 as well as PCl5 are possible. It is due to

Accepted Answer

availability of vacant d orbitals in P but not in N. Phosphorus has vacant d orbitals that allow it to expand its valence shell and accommodate more than four bonds, enabling the formation of PCl5. In contrast, nitrogen lacks these d orbitals, limiting it to a maximum of four bonds, which is why NCl5 cannot exist.

Question 42

What may be expected to happen when phosphine gas is mixed with chlorine gas ?

Accepted Answer

PCl3 and HCl are formed and the mixture warms up. Phosphine ignites in chlorine; the reaction PH3 + 3Cl2 -> PCl3 + 3HCl (and further PCl5) is strongly exothermic, so PCl3 and HCl form and the mixture warms up.

Question 43

Which among the following factors is the most important in making fluorine, the strongest oxidizing halogen ?

Accepted Answer

Bond dissociation energy. Fluorine's strong oxidizing ability is primarily due to its low bond dissociation energy, which allows it to easily break bonds and accept electrons from other substances, facilitating oxidation.

Question 44

Which of the following sequences gives the correct decreasing order of acid strength for these oxoacids?

Accepted Answer

HClO4 > HClO3 > HClO2 > HOCl. The correct order reflects the increasing number of oxygen atoms attached to the central chlorine atom, which enhances the acid strength due to greater electronegativity and stability of the conjugate base formed after deprotonation. HClO4, having the most oxygen atoms, is the strongest acid, followed by HClO3, HClO2, and finally HOCl, which has the least.

Question 45

Which one has the highest boiling point?

Accepted Answer

Xe. Among He, Ne, Kr, Xe the boiling point increases down the group because larger atoms are more polarizable and have stronger London dispersion forces. Xe, being the largest, has the highest boiling point.

Question 46

The pair in which phosphorus atoms have a formal oxidation state of +3 is:

Accepted Answer

Orthophosphorous and pyrophosphorous acids. Orthophosphorous and pyrophosphorous acids both contain phosphorus in a +3 oxidation state, as indicated by their chemical structures and the way phosphorus is bonded in these compounds.

Question 47

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

Accepted Answer

(NH4)2SO4. Ba(N3)2 -> Ba + 3N2, (NH4)2Cr2O7 -> N2 + Cr2O3 + 4H2O, and NH4NO2 -> N2 + 2H2O all release N2. (NH4)2SO4 on heating gives NH3 and H2SO4 (and NH4HSO4), never N2, so it is the compound that does not produce nitrogen gas.

Question 48

On heating, which of the following substances liberates ammonia gas?

Accepted Answer

(NH4)2SO4 Δ → 2NH3 + H2SO4. (NH4)2SO4 decomposes upon heating to produce ammonia gas and sulfuric acid, making it the only option that directly liberates ammonia.

Question 49

Calomel (Hg2Cl2) on reaction with ammonium hydroxide gives

Accepted Answer

HgNH2Cl. The reaction of calomel with ammonium hydroxide leads to the formation of mercuric amidochloride (HgNH2Cl) as it involves the substitution of chloride ions by the amine group from ammonium hydroxide.

Question 50

Match the catalysts (Column I) with products (Column II).
Column I
Catalyst
(A) V2O5
(B) TiCl4 / Al(Me)3
(C) PdCl2
(D) Iron Oxide
Column II
Product
(i) Polyethylene
(ii) ethanol
(iii) H2SO4
(iv) NH3

Accepted Answer

(A)-(iii); (B)-(i); (C)-(ii); (D)-(iv). The correct option matches each catalyst with its respective product based on their known chemical reactions: V2O5 is used in the production of sulfuric acid (H2SO4), TiCl4/Al(Me)3 is a catalyst for producing polyethylene, PdCl2 is involved in the synthesis of ethanol, and iron oxide is used in the Haber process to produce ammonia (NH3).

JEE Main Chemistry: The p-Block Elements questions with solutions

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