Find WBJEE Solved Physics and Chemistry Question Paper for the year 2016. This article contains ten questions from the Chemistry section of WBJEE 2016 question paper with their detailed solution. This previous year question paper will help aspirants in understanding exam pattern, question format, important topics and assessing their preparation. It has also been seen that sometimes questions are repeated in WBJEE Exam.
The Physics and Chemistry section of WBJEE engineering exam has 80 multiple choice questions. The first 40 questions are from Physics and the last 40 questions are from Chemistry.
The detailed solution from question #71 to #80 is provided in this article.
71. The major products obtained during ozonolysis of 2, 3 – dimethyl-1-butene and subsequent reductions with Zn and H2O are
(A) Methanoic acid and 2-methyl-2-butanone
(B) Methanal and 3-methyl-2-butanone
(C) Methanol and 2,2-dimethyl-3-butanone
(D) Methanoic acid and 2-methyl-3-butanone
Ans : (B)
The chemical reaction can be shown as below:
72. Identify X in the following sequence of reactions:
Ans : (B)
The chemical reaction can be shown as below;
73. Compound X is tested and the results are shown in the table :
aqueous sodium hydroxide is added, then heated gently
Gas given off which turns damp red litmus paper blue
dilute hydrochloric acid is added
effervescence, gas given off which turns lime water milky and acidified K2Cr2O7 paper green
Which ions are present in compound X?
(A) Ammonium ions and sulphite ions
(B) Ammonium ions and carbonate ions
(C) Sodium ions and carbonate ions
(D) Ammonium ions and sulphate ions
Ans : (A)
So, the compound X is ammonium chloride in first test.
So, the compound X is sulphite ion in the second test.
74. The time taken for an electron to complete one revolution in Bohr orbit of hydrogen atom is
75. Among the following, which should have the highest r.m.s. speed at the same temperature?
where, m is the molar mass of one molecule of the gas.
molar mass of SO2 = 64 g
molar mass of CO2 = 44 g
molar mass of O2 = 32 g
molar mass of H2 = 2 g
Since the molar mass of H2 is least so, it has highest rms speed
CATEGORY - III (Q76 to Q80)
One or more answer(s) is (are) correct. Correct answer(s) will fetch marks 2. Any combination containing one or more incorrect answer will fetch 0 marks. If all correct answers are not marked and also no incorrect answer is marked then score = 2 × number of correct answers marked / actual number of correct answers.
76. Amongst the following compounds, the one(s) which readily react with ethanolic KCN?
(A) Ethyl chloride
(B) Chloro benzene
(D) Salicylic acid
Ans : (A, C)
77. Choose the correct statements(s) among the following:
Ans : (B, D)
So, they are not enantiomers.
78. Which of the following statement(s) is (are) correct when a mixture of NaCl and K2Cr2O7 is gently warmed with conc. H2SO4?
(A) A deep red vapour is evolved.
(B) The vapour when passed through NaOH solution, gives a yellow solution.
(C) Chlorine gas is also evolved.
(D) Chromyl chloride is formed.
Ans : (A, B, D)
The reaction can be written as follows:
When potassium dichromate reacts with sodium chloride then a deep red vapour is evolved along with chromyl chloride and when this vapour is passed through NaOH solution then yellow solution of sodium chromate is formed.
Hence correct options are A, B and D
79. Of the following molecules, which have shape similar to CO2?
Ans : (A, C)
CO2 has linear molecular shape.
Let’s see the shape of all molecules given in the option:
Only options A and C have molecules that have linear shapes.
80. In which of the following mixed aqueous solutions pH = pKa at equilibrium?
(1) 100 ml of 0.1M CH3COOH + 100 ml of 0.1M CH3COONa
(2) 100 ml of 0.1M CH3COOH + 50 ml of 0.1M NaOH
(3) 100 ml of 0.1M CH3COOH + 100 ml of 0.1M NaOH
(4) 100 ml of 0.1M CH3COOH + 100 ml of 0.1M NH3
(A) (1) is correct
(B) (2) is correct
(C) (3) is correct
(D) Both (1) and (2) are correct
Ans: (A, B, D)
So, option A is correct.
So, option B is correct.