Скачать или смотреть WBJEE 2020 Paper Chemistry Solution | Chemistry | Part 3-4 | Q21-30 | Answer Key WB-JEE

Wbjee 2020 paper solution - Chemistry Part 3-4 by XCEL JEE Academy
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Questions 21-30 of WBJEE 2020 for Chemistry Part 3-4
21 Which of the following has the largest number of atoms ?
(A) 1 g of Ag (B) 1 g of Fe (C) 1 g of Cl2 (D) 1 g of Mg
22. Indicate the correct IUPAC name of the co-ordination compound shown in the figure.
(A) Cis-dichlorotetraminochromium (III) chloride
(B) Trans-dichlorotetraminochromium (III) chloride
(C) Trans-tetraminedichlorochromium (III) chloride
(D) Cis-tetraamminedichlorochromium (III) chloride
23. What will be the mass of one atom of 12C ?
(A) 1 a.m.u. (B) 1.9923 × 10–23g (C) 1.6603 × 10–22g (D) 6 a.m.u.
24. How and why does the density of liquid water change on prolonged electrolysis ?
(A) Decreases, as the proportion of H2O increases (B) Remains unchanged
(C) Increases, as the proportion of D2O increases (D) Increases, as the volume decreases
25. Bond order of He2, He2+ and He22+ are respectively :
(A) 1, 1/2, 0 (B) 0 , 1/2,1 (C) 1/2, 1, 0 (D) 1, 0, 1/2
26. To a solution of a colorless efflorescent sodium salt, when dilute acid is added, a colorless gas is evolved along with formation of a white precipitate. Acidified dichromate solution turns green when the colourless gas is passed through it. The sodium salt is:
(A) Na2SO3 (B) Na2S (C) Na2S2O3 (D) Na2S4O6
27. Obtaining Metal M from its oxide M2O3
thermite reaction
28. In the extraction of Ca by electro reduction of molten CaCl2 some CaF2 is added to the electrolyte for the following reason :
(A) To keep the electrolyte in liquid state at temperature lower than the m. p. of CaCl2
(B) To effect precipitation of Ca (C) To effect the electrolysis at lower voltage
(D) To increase the current efficiency
29. The total number of alkyl bromides (including stereo isomers) formed in the reaction: Me3C – CH = CH2 + HBr → will be:
(A) 1 (B) 2 (C) 3 (D) No bromide forms
30. Mg/diethyl ether - Grignard reagent

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