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Class 12 Chemistry Question Answers

Question Answer

Class 12

Chemistry

Master Class 12 Chemistry: Eng...

Class 12 Chemistry Question Answers

What is standard hydrogen electrode ?

Molecular mass of Benzene is ……………..g\/molA. 72B. 78 C. 79D. 77

Evaporation is a surface phenomenon. Explain.

Nylon is an example of thermoplastic$(a){\\text{ True}} \\\\{\\text{(b) False}} \\\\ $

What is the geometry of the chromate ion?A. TetrahedralB. OctahedralC. Trigonal planarD. Linear

In the Castner process for the extraction of sodium the anode is made up of ………… metal.a.) Copperb.) Carbonc.) Sodiumd.) Nickel

Explain why Nitrolim is used as a fertiliser.

Which of the following is not a Noble gas?A. HeliumB. NeonC. ArgonD. Hydrogen

The conductivity of an electrolytic solution decreases on dilution due to:a.) Decreases in number of ions per unit volumeb.) Increases in ionic mobility of ions c.) Increase in percentage ionizationd.) Increase in number of ions per unit volume

The type of glass used in making lenses and prisms is:a.) A flint glassb.) Jena glassc.) Pyrex glassd.) Quartz glass

Identify the Number of pi bonds in the cyclic structure of $S_3$$O_9$.

Give simple chemical tests to distinguish between the following pairs of compounds.a.) Propanal and Propanoneb.) Acetophenone and Benzophenonec.) Phenol and Benzoic acidd.) Benzoic acid and Ethyl benzoatee.) Pentan-2-one and Pentan-3-onef.) Benzaldehyde and Acetophenoneg.) Ethanal and Propanal

\"Middle row anomaly\" is related with: This question has multiple correct options A. Stability of transition metal oxides B. Stability of alkali metal oxides C. Instability of halogen oxides D. Stability of alkaline earth metal oxides

The correct chemical formula of ammonium phosphate is:a.) \\[{N_2}{H_6}P{O_4}\\]b.) \\[{(N{H_3})_3}P{O_4}\\]c.) \\[{(N{H_4})_3}P{O_4}\\]d.) \\[{(N{H_4})_2}P{O_4}\\]

What does soda water contain?(A). Carbonic acid(B). Sulphuric acid(C). Carboxylic acid(D). Nitrous acid

Phenolphthalein in acid shows: a.) blue b.) red c.) pink\/purple d.) colorless e.) orange

AgCl and NaCl are colourless. NaBr and NaI are colourless but AgBr and AgI are coloured. This is because:a.) \\[A{g^ + }\\] polarises \\[B{r^ - }\\] and \\[{I^ - }\\]b.) \\[A{g^ + }\\] has unpaired d – orbital.c.) \\[A{g^ + }\\] depolarises \\[B{r^ - }\\] and \\[{I^ - }\\]d.) None of the above is correct

Sulfuric acid is produced by lead chamber process with following exothermic reaction$2\\text{S}{{\\text{O}}_{2}}+{{\\text{O}}_{2}}\\overset{\\text{NO}}{\\leftrightarrows}2\\text{S}{{\\text{O}}_{3}}\\overset{\\text{ }{{\\text{H}}_{2}}\\text{O }}\\longrightarrow{{\\text{H}}_{2}}\\text{S}{{\\text{O}}_{4}}$ What is the role of NO in the given exothermic reaction?(a) Oxidising agent(b) Reducing agent(c) Catalyst(d) None of these

Which of the following will react most readily with HI?a.) $\\text{C}{{\\text{H}}_{\\text{3}}}\\text{OH}$b.) ${{\\left( \\text{C}{{\\text{H}}_{\\text{3}}} \\right)}_{\\text{3}}}\\text{COH}$c.) $\\text{C}{{\\text{H}}_{\\text{3}}}\\text{C}{{\\text{H}}_{\\text{2}}}\\text{OH}$d.) ${{\\left( \\text{C}{{\\text{H}}_{\\text{3}}} \\right)}_{\\text{2}}}\\text{CHOH}$

Name two gases which can be used in the study of the fountain experiment.A. Ammonium chloride and hydrogen chloride gas.B. Ammonia and hydrogen chloride gas.C. Ammonia gas and chlorine gas.D. Ammonia gas and hydrogen gas.

What is the effect of Frenkel defect on the density of ions solids?(a) The density of the crystal increases.(b) The density of the crystal decreases.(c) The density of the crystal remains unchanged.(d) There is no relationship between density of a crystal and defect present in it.

An example of secondary battery cell is:A.Edison Alkaline cellB.Daniel cellC.Lechanche cellD.Bunsen cell

An aqueous solution contains an unknown concentration of \\[B{{a}^{+2}}\\]. When 50 mL of a 1 M solution of \\[N{{a}_{2}}S{{O}_{4}}\\] is added \\[BaS{{O}_{4}}\\] just begins to precipitate. The final volume is 500 ml. The solubility product of \\[BaS{{O}_{4}}\\] is \\[1\\times {{10}^{-10}}\\]. Find the concentration of \\[B{{a}^{+2}}\\]in the original solution?\\[a)~~~~1.1\\times {{10}^{-9}}M\\]\\[b)\\text{ }1.0\\times {{10}^{-10}}M\\]\\[c)~~~~5\\times {{10}^{-9}}M\\]\\[d)~~~2\\times {{10}^{-9}}M\\]

The insecticide Gammexane is:A. DDTB. Benzene hexachlorideC. ParathionD. Chloral

The ease of dehydrohalogenation of alkyl halide with alcoholic KOH is:A. \\[{3^0} {2^0} {1^0}\\]B. \\[{3^0} {2^0} {1^0}\\]C. \\[{3^0} {2^0} {1^0}\\]D. \\[{3^0} {2^0} {1^0}\\]

How can ethanol be converted to propanone?

The IUPAC name of $[Ni(CO)_4]$ and $[PtCl_4]^{2−}$.

Which one of the following complexes will most likely absorb the visible light?[Atomic numbers: Sc = 21 Ti = 22 V = 23 Zn = 30]A. \\[{[Sc{({H_2}O)_6}]^{ + 3}}\\]B. \\[{[Ti{(N{H_3})_6}]^{ + 4}}\\]C. \\[{[V{(N{H_3})_6}]^{ + 2}}\\]D. \\[{[Zn{(N{H_3})_6}]^{ + 2}}\\]

Which of the following noble gases is used in the treatment of cancer?A. XeB. ArC. RnD. Kr

Ethyne on passing through a red hot iron tube gives:A. MesityleneB. BenzeneC. ButenyneD. None

The coordination number of cation and anion in fluorite $(Ca{F_2}){\\text{ and CsCl}}$ are respectively:$(a){\\text{ 8:4 and 6:3}} \\\\(b){\\text{ 6:3 and 4:4}} \\\\(c){\\text{ 8:4 and 8:8}} \\\\(d){\\text{ 4:2 and 2:4}} \\\\ $

The magnetic behaviour or geometry of the complex $\\left[ {Ni{{\\left( {CO} \\right)}_4}} \\right]$ is-A. Square planar geometry and paramagneticB. Square planar geometry and diamagneticC. Tetrahedral geometry and paramagneticD. Tetrahedral geometry and diamagnetic

A toxic gas with rotten egg-like smell ${{\\text{H}}_2}{\\text{S}}$ is used for qualitative analysis. If the solubility of ${{\\text{H}}_2}{\\text{S}}$ in water at STP is 0.195 m. Calculate Henry’s law constant.

What are the hybridizations of ${\\text{ICl}}_2^ - $ and ${\\text{ClO}}_4^ - $ respectively?${\\text{A}}{\\text{. s}}{{\\text{p}}^3}{{\\text{d}}^2}{\\text{ s}}{{\\text{p}}^3} \\\\{\\text{B}}{\\text{. s}}{{\\text{p}}^2}{\\text{ s}}{{\\text{p}}^3}{\\text{d}} \\\\{\\text{C}}{\\text{. s}}{{\\text{p}}^3}{\\text{d s}}{{\\text{p}}^3} \\\\ $${\\text{D}}{\\text{.}}$ None of these

Which of the following are the demerits of the Mendeleev periodic table?(a) No proper position of hydrogen is given(b) Grouping of chemically dissimilar elements(c) Position given to isotopes(d) Presence of anomalous pairs

Which of the following is not an example of thermite reaction?(a) $\\text{C}{{\\text{r}}_{2}}{{\\text{O}}_{3}}+2\\text{Al}\\to \\text{A}{{\\text{l}}_{2}}{{\\text{O}}_{3}}+2\\text{Cr}$(b) $\\text{3M}{{\\text{n}}_{3}}{{\\text{O}}_{4}}+8\\text{Al}\\to \\text{4A}{{\\text{l}}_{2}}{{\\text{O}}_{3}}+9\\text{Mn}$(c) $2\\text{HgO+HgS}\\to \\text{3Hg+S}{{\\text{O}}_{2}}$(d) $2\\text{C}{{\\text{u}}_{2}}\\text{S+3}{{\\text{O}}_{2}}\\to 2\\text{C}{{\\text{u}}_{2}}\\text{O+S}{{\\text{O}}_{2}}$

Alcoholic KOH is used for:(A) Dehydration(B) Dehydrogenation(C) Dehydrohalogenation(D) Dehalogenation

Cooking gas is a mixture of:A. Carbon monoxides and carbon dioxideB. Butane and propaneC. Methane and ethylene D. Carbon dioxide and oxygen

Gatterrmann reaction is given by:A. \\[{{C}_{6}}{{H}_{6}}\\]B. \\[{{C}_{6}}{{H}_{6}}-C{{H}_{3}}\\]C. \\[{{C}_{6}}{{H}_{6}}-Cl\\]D. All of these

Which of the following has the highest boiling point?A.1-ChloropentaneB.2-chloropentaneC.3-chloropentaneD.All have equal boiling point

What is the IUPAC nomenclature of $Ni{\\left( {CO} \\right)_4}$ ?(A) Tetracarbonyl Nickel (I)(B) Tetracarboxy Nickel (0)(C) Tetracarbonyl Nickel (0)(D) None of these

Milk is an emulsion in which :A . a gas is dispersed in water B . lactose is dispersed in waterC . milk fat is dispersed in waterD . a solid is dispersed in water

If the radius of \\[N{{a}^{+}}\\]is 95 pm and that of \\[C{{l}^{-}}\\]is 181 pm then:A. coordination number of \\[N{{a}^{+}}\\]is 6B.coordination number of \\[C{{l}^{-}}\\]is 8C.length of the unit cell is 552 pm D.length of the unit cell is 380 pm

Write the IUPAC names of the following components and classify them into primary and tertiary amines-(A) ${\\left( {C{H_3}} \\right)_2}CHN{H_2}$(B) $C{H_3}{(C{H_2})_2}N{H_2}$(C) $C{H_3}NHCH{(C{H_3})_2}$(D) ${\\left( {C{H_3}} \\right)_3}CN{H_2}$(E) ${C_6}{H_5}NHC{H_3}$(F) ${\\left( {C{H_3}C{H_2}} \\right)_2}NC{H_3}$(G) $m - Br{C_6}{H_4}N{H_2}$

Define chemical twins. Write the general electronic configuration of actinoids.

${\\text{Ethanol}}\\xrightarrow{{{P_4}\/{I_2}}}X\\xrightarrow[{HBr}]{{KOH\\left( {alc.} \\right)}}Y$In this sequence of reaction Y is:a.) Etheneb.) Bromoethanec.) Ethanold.) None of these

Which of the following compounds does not undergo Hell-Volhard-Zelinsky reaction?${\\text{A}}{\\text{.}}$ Ethanoic acid${\\text{B}}{\\text{.}}$ Propionic acid${\\text{C}}{\\text{.}}$ Iso-butyric acid${\\text{D}}{\\text{.}}$ Trichloroacetic acid

Butter of tin is:a.) \\[SnC{{l}_{2}}.5{{H}_{2}}O\\]b.) \\[SnC{{l}_{2}}\\]c.) \\[SnC{{l}_{4}}\\]d.) \\[SnC{{l}_{4}}.5{{H}_{2}}O\\]

Hydrolysis of \\[NC{{l}_{3}}\\] gives \\[N{{H}_{3}}\\] and X. Which of the following is X?a.) \\[HCl{{O}_{4}}\\]b.) \\[HCl{{O}_{3}}\\]c.) HOCld.) \\[HCl{{O}_{2}}\\]

A metal used in storage batteries is:A.\t$Cu$B.\t$Pb$C.\t$Sn$D.\t$Ni$

The bonds present in borazine or inorganic benzene are:A. $12\\sigma ~3\\pi $B. $9\\sigma ~6\\pi $C. $6\\sigma ~6\\pi $D. $9\\sigma ~9\\pi $

During electrolytic refining of zinc it gets:A. Deposited on cathodeB. Deposited on anodeC. Deposited on cathode as well as anodeD. Remains in the solution

Which of the following is not a chemical change?(A) Sublimation(B) Combustion(C) Electrolysis(D) Rusting

An example of lyophilic colloid is:A.colloidal solutions of metalB.sulphur in waterC.gelatinD.$Fe{(OH)}_{3}$

Distinguish between the true solution and colloidal solution.

The order of electronegativity for halogens is A.F Cl Br IB.I Br Cl FC.I Cl Br FD.Cl F Br I

Write the name of two metals that are used in maximum composition in mischmetal?

Which of the following properties is different between two members of a homologous series?(A) General Formula(B) Molecular weights(C) Methods of preparation(D) Chemical properties

Benzyl chloride ${C_6}{H_5}C{H_2}Cl$ can be prepared from toluene by chlorination with :A. $C{l_2}$B. $S{O_2}C{l_2}$C. $SOC{l_2}$D. $NaOCl$

Laughing gas is _______a.) Nitrogen pentoxideb.) Nitrous oxide c.) Nitrogen trioxided.) Nitric oxide

Which of the following is most soluble in water? a.) n-butyl alcoholb.) Iso-butyl alcoholc.) Tertiary butyl alcohold.) None of these

Proteins are the polymers of __________.A. FormaldehydesB. Secondary aminesC. Amino acidsD. Ammonia

Write the definition of Kohlrausch law of independent migration of ions.

The extremely high melting point of diamond (carbon) may be explained by the:A. Network covalent bondsB. Ionic bondsC. Hydrogen bondsD. Van der Waals forcesE. None of the above

The full form of ATP is Adenosine triphosphate. If true enter 1 else enter 0.

Differentiate true solution and colloidal solution.

How is \\[C{{O}_{2}}\\] gas tested in the laboratory?

Dettol is a mixture of:A) Chloroxylenol and terpineol in a suitable solvent.B) Formaldehyde and phenol in the solvent waterC) Tincture of iodine and chloroformD) \\[KMn{{O}_{4}}\\] and iodoform.

Give the structure of sucrose.

A white precipitate insoluble in \\[HN{{O}_{3}}\\] is formed when the aqueous solution of x in NaOH is treated with barium chloride and bromine water. So x is :A. $S{{O}_{3}}$\tB. $S{{O}_{2}}$C. $C{{O}_{2}}$D. None of the above

Question: Geometry of $B{F_3}$ isA: Trigonal planarB: Pentagonal C: LinearD: Tetrahedral

Explain addition polymers with an example?

Which of the following ether is called phenetole?[A]$PhOC{{H}_{3}}$[B]$PhO{{C}_{2}}{{H}_{5}}$[C]$PhO{{C}_{3}}{{H}_{7}}$[D]$p-N{{O}_{2}}-{{C}_{6}}{{H}_{4}}-O{{C}_{2}}{{H}_{5}}$

Glycerine contains which type of one hydroxyl group?A. SecondaryB. PrimaryC. TertiaryD. None of these

Explain HVZ reaction with example.

Write the chemical name of one antifertility drug.

What is the difference between physisorption and chemisorption?

How is Methoxyethane prepared from:(a) Methyl iodide (b) Diazomethane

The terms order and molecularity are common in chemical kinetics.(A) What do you mean by order and molecularity?(B) (1) Write two factors influencing rate of reaction.(2) Write Arrhenius equation

Ethylene glycol is used as an antifreeze agent. Calculate the amount of ethylene glycol used to be added to ${ 4kg }$ of water to prevent it from freezing at ${ -6 }^{ \\circ }{ C }$ ${ K }_{ f }$ for water = ${ 1.85Kmol }^{ -1 }{ Kg }$

What are the main constituents of dettol?

What happens when? (1) \\[PC{l_5}\\] is heated(2) ${H_3}P{O_3}$ is heated?Write the reaction involved.

2-Bromopentane is treated with an alcoholic KOH solution. What will be the major product formed in this reaction and what is this type of elimination called?(A.) Pent-1-ene $\\beta$- Elimination(B.) Pent-2-ene $\\beta$- Elimination(C.) Pent-1-ene Nucleophilic substitution(D.) Pent-2-ene Nucleophilic substitution

(a) Explain the condensation polymer by an example.(b) Give one example each of thermoplastic and thermosetting polymers.(c) Give the names of monomers used for obtaining Buna-N.

Give preparation and uses of Nylon 6 6.

Correct order of electrophilic substitution reaction?\n \n \n \n \n A. \\[abcd\\]B. \\[dbac\\]C. \\[bacd\\]D. \\[badc\\]

At which temperature chemical adsorption occurs?A. Very low temperatureB. High temperatureC. Low temperatureD. Temperature does not affect

The number of hydrogen bonds between Guanine and Cytosine; and between Adenine and Thymine in DNA are:A.${ 1 2 }$B.${ 3 2 }$C.${ 3 1 }$D.${ 2 1 }$

Write the mechanism of hydration of ethene to yield ethanol.

Enzymes are made up of?(A) Edible proteins(B) Proteins with specific structure(C) Nitrogen containing carbohydrates(D) Carbohydrates

\\[\\text{KMn}{{\\text{O}}_{4}}\\](acidic\/alkaline) is not decolourised by:A. Mohr saltB. Oxalic acidC. BenzeneD. Propene

What is the structural difference between high density polythene (HDP) and low density polythene (LDP)?

Reaction of bromine water phenol gives white ppt of:A. o – bromophenolB. p – bromophenolC. 2 4 6 – tribromophenolD. m – bromophenol

Among the given reactions which is faster and why?i. \\[Me-CHCl-Me\\xrightarrow{alc.KOH}C{{H}_{3}}-CH=C{{H}_{\\begin{smallmatrix}2 \\\\ \\end{smallmatrix}}}\\]ii. \\[C{{H}_{3}}-C{{H}_{2}}-C{{H}_{2}}-Cl\\xrightarrow{alc.KOH}C{{H}_{3}}-CH=C{{H}_{2}}\\]

In a catalytic conversion of ${N_2}$ to $N{H_3}$ by Haber's process the rate of reaction was expressed as change in the concentration of ammonia per time is $40 \\times {10^{ - 3}}{\\text{ }}mol{\\text{ }}{L^{ - 1}}{\\text{ }}{s^{ - 1}}$ . If there is no side reaction the rate of the reaction as expressed in terms of hydrogen is:(in $mol{\\text{ }}{L^{ - 1}}{\\text{ }}{s^{ - 1}}$)\\[A.{\\text{ }}60 \\times {10^{ - 3}} \\\\B.{\\text{ }}20 \\times {10^{ - 3}} \\\\C.{\\text{ }}1.200 \\\\D.{\\text{ }}10.3 \\times {10^{ - 3}} \\\\ \\]

Name a salt of a strong acid like \\[HN{{O}_{3}}\\] and a weak base like \\[N{{H}_{4}}OH\\]. Represent the reaction that takes place.

Which is an example of auto catalyst?A. Hydrolysis of ethyl acetateB. Decomposition of TNG C. Oxidation of oxalic acid D. All of the above

Write about Gabriel phthalimide synthesis ?

The Oxidation State and Effective Atomic Number (EAN) of Cobalt in \\[{[Co{F_6}]^{ - 2}}\\]are respectivelyA.3 and 36B.4 and 35C.4 and 37D.2 and 35

The following diagram represents the industrial preparation of nitric acid from ammonia \\[N{H_3} + {O_2}\\] (from excess of air).\\[\\mathop {N{H_3} + {O_2}}\\limits_{(excess{\\text{ }}air)} \\xrightarrow[{(900^\\circ C)}]{{(A)}}NO\\xrightarrow[{Air}]{{(B)}}(C)\\xrightarrow[{water}]{}HN{O_3} + NO\\]Which of the following options correctly describes the reagents products and reaction conditions?A.A – Catalyst and high pressure B – Cool C – \\[N{O_2}\\]B.A – Catalyst B – Cool C – \\[N{O_2}\\]C.A – Catalyst and high pressure B – high pressure C – \\[N{O_2}\\]D.A –high pressure B – Catalyst C – \\[{N_2}{O_3}\\]\t