JEE Main Previous Year Papers Questions With Solutions Chemistry Elements of p-Block: Groups 13,14,15,16,17 and 18
1.When H2S is passed through Hg2S we get(2002)
(1)HgS 2) HgS + Hg2S
3) Hg2S 4) Hg2S2
2.Alum helps in purifying water by (2002)
(1)forming Si complex with clay particles
(2)sulphate part which combines with the dirt and removes it
(3)coagulating the mud particles
(4)making mud water soluble
Ans.(3) Alum fumisheds Al3+ ions which bring about coagulation of negatively charged clay poarticles bacteria etc.
3.In case of nitrogen, NC13 is possible but not NC1S while in case of phosphorous, PC13 as well as PC15 are possible. It is due to (2002)
(1)availability of vacant d orbitals in P but not inN
(2)lower electronegativity of P than N
(3)lower tendency of H-bond formation in P than N
(4)occurrence of P in solid while N in gaseous state at room temperature
Ans.(1) 7N2 =ls22s23p3, 15P = 1 s22s22p63s23p3 In phosphorous the 3d – orbitals are available
4.Number of sigma bonds in P4O10 is (2003)
(1)6 2) 1 3) 17 4) 16 Ans.
5.What’happens when phosphine gas is mixed with chlorine gas ? (2003)
(1)PC13 an HC1 are formed and the mixture warms up
(2)PC15 and HC1 are formed and the mixture cools down
(3)PH3.C12 is formed with warming up
(4)The mixture only cools down
6.Graphite is a soft solid lubricant extremely difficult to melt. The reasong for this anomalous behavior is that graphite. (2003)
(1)is an alio tropic form of diamond
(2)has molecules of variable molecular masses like polymers
(3)has carbon atoms arranged in large plates of rings of strongly bound carbon atoms with weak interplate bonds.
(4)is a non-crystalline substance.
Ans.(1) 4HC/ + 02–> 2Cl2 + 2H20 cloud of white fumes.
7.Concentrated hydrochloric acid when kept in open air sometimes produces a cloud of white fumes. The explanation for it is that (2003)
(1)oxygen in air reacts with the emitted HC1 gas to form a cloud of chlorine gas
(2)Strong affinity of HC1 gas for moisture in air results in forming of droplets of liquid solution which appears like a cloudy smoke.
(3)due to strong affinity for water. Concentrated hydrochloric acid pulls moisture of air towards itself. This moisture forms droplets of water and hence the cloud.
(4)concentrated hydrochloric acid emits strongly smelling HC1 gas all the time.
Ans.(3) Layers are held together.
8.Glass is a (2003)
(1)super -cooled liquid 2) gel
Ans.(1) Glass is a transparent or translucent super cooled liquid.
9.For making good quality mirrors plates of float glass are used. These are obtained by floating molten glass over a liquid metal which does not solidify before glass. The metal used can be (2003)
(1)tin 2) sodium
3) magnesium 4) mercury
Ans.(4) It is because mercury exists as liquid at room temperature.
10.Which among the following factors is the mostimportant in making fluorine the strongest oxidizing halogen?(2004)
(2)Bond dissociation energy
(3)Hydration enthalpy 4) Ionization enthalpy
Ans.(2) Lower dissociation energy of bonds in F2.
11.Which one the following statement regarding helium is incorrect ? (2004)
(1) It is used to fill gas balloons instead of H2because it is lighter and non-inflammable
(2)It is used in gas-cooled nuclear reactors
(3)It is used to produce and sustain powerful superconducting reagents (4)It is used as cryogenic agent for carrying out experiments at low temperatures
Ans.(1) Hydrogen is lightest and is non inflamable.
Ans.(4) Hydrated and coordinated aluminium cation is farmed
13.The soldiers of Napolean army while at Alps during freezing winter suffered a serious problem as regards to the tin buttons of their uniforms. White metallic tin buttons got converted to grey powder. This transforma tion is related to(2004)
(1)an interaction with nitrogen of the air at very low temperatures
(2)an interaction with water vapour contained in the humid air
(3)a change in the partial pressure of oxygen in the air
(4)a change in the crystalline structure of tin
Ans.(4) Transformation of crystal structure.
14.The number of hydrogen atom(s) attached to phosphorus atom in hypophosphorous acid is
(1)zero 2) two 3) one 4) three
15.The correct order of the thermal stability ofhydrogen halides (H – X) is (2005)
(1)HI > HBr > HC1 > HF
(2)HF > HC1 > HBr > HI
(3)HC1 < HF > HBr < HI
(4)HI > HC1 < HF < HBr
Ans.(2) HF is most stable.
16.Heating an aqueous solution of aluminiumchloride to dryness will give (2005)
(1)A1C13 2) A12C16
3) A1203 4) Al(OH)CI2
17.In silicon dioxide (2005)
(1)Each silicon atom is surrounded by four oxygen atoms and each oxygen atom is bonded to two silicon atoms
(2)Each silicon atom is surrounded by two oxygen atoms and each oxygen atom is bonded to two silicon atoms
(3)Silicon atoms is bonded to two oxygen atoms
(4)There are double bonds between silicon and oxygen atoms
18.The structure of diborane (B2Hfi) contains(2005)
(1)four 2c-2e bonds and two 3c-2e bonds
(2)two 2c-2e bonds and four 3c-2e bonds
(3)two 2c-2e bonds and two 3c-3e bonds
(4)four 2c-2e bonds and four 3c-2e bonds
19.Which of the following chemical reactions depicts the oxidizing behaviour of H2S04 ?
(1)2HI + H2S04 -> I2 + S02 + 2H20 (2006)
(2)Ca(OH)2 + H2S04 CaS04 + 2H20
(3)NaCl + H2S04 NaHS04 + HC1
(4)2PC1S + H2S04 2POCl3 + 2HC1 + S02C12
20.A metal, M forms chlorides in its +2 and 44 oxidation states. Which of the following statements about these chlorides is correct ?
(1)MC12 is more volatile than MC14 (2006)
(2)MC12 is more soluble in anhydrous ethanol than MC14
(3)MC12 is more ionic than MC14
(4)MC12 is more easily hydrolysed than MC14
21.Which of the following statements is true ?
(1)H3PO3 is a stronger acid than H2S03 (2006)
(2)In aqueous medium HF is a stronger acid than HC1
(3)HC104 is a weaker acid than HC103
(4)HNO3 is a stronger acid than HN02
22.What products are expected from the disproportionation reaction of hypochlorous acid ? (2006)
(1)HCIO3 and C120 2) HC102 and HC104
3) HC1 and C120 4) HC1 and HC103
23.The decreasing values of bond angles from NH3 (106 °) to SbH3 (101 °) down group-15 of the periodic table is due to (2006)
(!)increasing bp-bp repulsion
(2)increasing p-orbital character in sp3
(3)decreasing lp-bp repulsion
Ans.(4) Repulsions will be less with lower electronagativity.
26.Identify the incorrect statement among the fol lowing (2007)
(1)Ozone reacts with S02 to give S03
(2)Silicon reacts with aqueous NaOH in the presence of air to give NajS^ and H20
(3)Cl2 reacts with excess of NH3 to give N2 and HC1
(4)Br2 reacts with hot and strong NaOH solu tion to give NaBr, NaBr04 and H20
28.Which one of the following is the correct statement ? (2008)
(1)Boric acid is a protonic acid
(2)Beryllium exhibits coordination number of six.
(3)Chlorides of both beryllium and aluminium have bridged chloride structures in solid phase
(4)B2H6.2NH3 is known as â€˜inorganic benzene’.
29.In which of the following arrangements, the e sequence is not strictly according to the property written against it ? (2009)
(1)C02 < Si02 < Sn02 < Pb02 : increasing oxidising power
(2)HF < HC1 < HBr < HI : increasing acid strength
(3)NH3 < PH3 AsH3 < SbHj : increasing basic strength
(4)B<C<0<N: increasing first ionization enthalpy
Ans.(1) Xe03 is more stable than XeF6. All the remaining reactions are feasible
33.Which of the following statements regarding sulphur is incorrect ? (2011)
(1)At 600 °C the gas mainly consists of S2 molecules
(2)The oxidation state of sulphur is never less than + 4 in its compounds
(3)S, molecule is paramagnetic
(4)The vapour at 200 °C consists mostly of S8 rings
Ans.(2) Sulphur can exhibit – 2, + 2, + 1 oxidation states also.
Ans.(3) Stability of VA group hybrides decreases from NH3 to BiH3 due to the decrease in M – H bond energy.
NH3 > PH3 > AsH3 > SbH3 > BiH3
35.Which of the following on thermal decomposition yields a basic as well as an acidic oxide ? (2012)
1) NaN03 2) KC103
3) CaC03 4) NH4N03
Ans.(1) ONF and ONO– are isoelectronic ON Cl and ONS– are isoelectronic
37.Which one of the following properties is not shown by NO ? (2014)
(1)It’s bond order is 2.5 .
(2)It is diamagnetic in gaseous state
(3)It is a neutral oxide
(4)It combines with oxygen to form nitrogen dioxide
Ans.(2) NO is paramagnetic.
38.Among the following oxoacids, the correct decreasing order of acid strength is (2014)
(1)HC102 > HC104 > HCIO, > HOC1
(2)HCIO > HC102 > HCIO3 > HOCl4
(3)HC104 > HCIO > HC102 > HOCl3
(4)HC102 > HCIO3 > HC102 > HOC1
Ans.(4) With an increase in unprotonated oxygen atoms, acidic strength increases.
39.In the context of the Hall-Heroult process for the extration of Al, which of the following statements is false? (2015)
(1)CO and C02 are produced in this process
(2)A/203 is mixed with CaF2 which lowers the melting point of the mixture and brings conductivity
(3)A/3+ is reduced at the cathode to form Al
(4)Na3A/F6 is serves as the electrolyte
Ans. A/203 is dissolved in cryolite which serves as electrolyte in molten state.
40.Which among the following is the most reactive ? (2015)
1) C/2 2) Br2 3) I2 4) ICI
Ans. Interhalogen compounds are polar and are more reactive.
41.Which one has the highest boiling point ?(2015)
(1) He 2) Ne 3) Kr (4) Xe
Ans. Boiling point increases with an increase in Molecular mass.
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