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WBJEE 2015 Solved Chemistry Question Paper – Part 7

Mar 7, 2017 14:46 IST

    Find WBJEE 2015 Solved Chemistry Question Paper – Part 7 in this article. This paper consists of 5 questions (#71 to #75) from WBJEE 2015 Chemistry paper. Detailed solution of these questions has been provided so that students can match their solutions.

    Importance of Previous Years’ Paper:

    Previous years’ question papers help aspirants in understanding exam pattern, question format, important topics and assessing preparation. It has also been seen that sometimes questions are repeated in WBJEE Exam. So, this paper will certainly boost your confidence.

    About WBJEE Exam

    WBJEE is a common entrance examinations held at state level for admission to the Undergraduate Level Engineering and Medical courses in the State of West Bengal. The Chemistry section of WBJEE 2015 engineering entrance exam consists of 40 questions.

    71. Addition of sodium thiosulphate solution to a solution of silver nitrate gives ‘X’ as white percipitate, insoluble in water but soluble in excess thiosulphate solution to give ‘Y’. On boiling in water, ‘Y’ gives ‘Z’. ‘X’, ‘Y’ and ‘Z’ respectively, are

    (A) Ag2S2O3, Na3[Ag(S2O3)2], Ag2S

    (B) Ag2SO4, Na[Ag(S2O3)2], Ag2S2

    (C) Ag2S2O3, Na5[Ag(S2O3)3], AgS

    (D) Ag2SO3, Na3[Ag(S2O3)2], Ag2O

    Ans : (A)

    Sol:

    The chemical reaction can be shown as follows:

    WBJEE 2015, Chemistry

    72. At temperature of 298 K the emf of the following electrochemical cell

    Ag(s) | Ag+ (0.1 M) | |Zn2+(0.1M) | Zn(s) will be (given Eocell= – 1.562 V)

    (A) – 1.532 V

    (B) – 1.503 V

    (C) 1.532 V

    (D) – 3.06 V

    Ans : (A)

    Sol:

    WBJEE 2015, Chemistry

    WBJEE 2016 Solved Physics and Chemistry Question Paper

    73. For the reaction X2Y4(I) → 2 XY2(g) at 300 K the values of ΔU and ΔS are 2 kCal and 20 Cal K–1 respectively. The value of ΔG for the reaction is

    (A) – 3400 Cal

    (B)  3400 Cal

    (C) – 2800 Cal

    (D) 2000 Cal

    Ans : (C)

    Sol:

    We have the reaction,

    X2Y4(I) → 2 XY2(g)

    WBJEE 2015, Chemistry

    74. The total number of aromatic species generated in the following reactions is

    WBJEE 2015, Chemistry

    (A) Zero

    (B) 2

    (C) 3

    (D) 4

    Ans : (C)

    Sol:

    WBJEE 2015, Chemistry

    So, total number of aromatic species generated in the given reactions is 3.

    75. Roasted copper pyrite on smelting with sand produces

    (A) FeSiO3 as fusible slag and Cu2S mattee’

    (B) CaSiO3 as infusible slag and Cu2O mattee’

    (C) Ca3(PO4)2 as fusible slag and Cu2S mattee’

    (D) Fe3(PO4)2 as infusible slag and Cu2S mattee’

    Ans : (A)

    Sol:

    During the process of extraction of copper from sulphide ores by the process of smelting the roasted ore is mixed with coke and silica (sand) SiO2 and is introduced into a blast furnace with 1200oC. The hot air is blasted and FeO is converted in to ferrous silicate.

    The reaction taking place in furnace is;

    FeO + SiO2 → FeSiO3

    Cu2O + FeS → Cu2S + FeO

    FeSiO3 as fusible slag floats over the molten matte of copper.

    Also Get:

    WBJEE Sample Papers

    WBJEE Previous Years' Question Papers

    WBJEE Online Test

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