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September 3 Shift 2 - Chemistry

Question 1: The five successive ionization enthalpies of an element are 800, 2427, 3658, 25024 and 32824 kJ mol^–1. The number of valence electrons in the element is:

1) 2
2) 4
3) 3
4) 5

Solution:

Answer: (3)

Fourth & Fifth I.E. are very high (periodic properties) indicating the presence of three valence shell electrons.

Question 2: The incorrect statement is:

1) Manganate and permanganate ions are tetrahedral
2) In manganate and permanganate ions, the -bonding takes place by the overlap of p orbitals of oxygen and d-orbitals of manganese
3) Manganate and permanganate ions are paramagnetic
4) Manganate ion is green in colour and permanganate ion is purple in colour

Solution:

Answer: (3)

Question 3: Match the following drugs with their therapeutic actions:

(i) Ranitidine (a) Antidepressant

(ii) Nardil (Phenelzine) (b) Antibiotic

(iii)Chloramphenicol (c) Antihistamine

(iv) Dimetane (Brompheniramine) (d) Antacid

(e) Analgesic

1) (i)-(d); (ii)-(a); (iii)-(b); (iv)-(c)
2) (i)-(d); (ii)-(c); (iii)-(a); (iv)-(e)
3) (i)-(a); (ii)-(c); (iii)-(b); (iv)-(e)
4) (i)-(e); (ii)-(a); (iii)-(c); (iv)-(d)

Solution:

Answer: (1)

Question 4: An ionic micelle is formed on the addition of

1) liquid diethyl ether to aqueous NaCl solution
2) sodium stearate to pure toluene
3) excess water to liquid
4) excess water to liquid

Solution:

Answer: (3)

The ionic micelles formed by the addition of water to soap {sodium stearate}.

Question 5: Among the statements (I–IV), the correct ones are:

(I) Be has a smaller atomic radius compared to Mg.

(II) Be has higher ionization enthalpy than Al.

(III) Charge/radius ratio of Be is greater than that of Al.

(IV) Both Be and Al form mainly covalent compounds.

1) (I), (II) and (IV)
2) (I), (II) and (III)
3) (II), (III) and (IV)
4) (I), (III) and (IV)

Solution:

Answer: (1)

Refer S-Block

Question 6: Complex A has a composition of H₁₂O₆Cl₃Cr. If the complex on treatment with conc. H2SO4 loses 13.5% of its original mass, the correct molecular formula of A is: [Given: the atomic mass of Cr = 52 amu and Cl = 35 amu]

1) [Cr(H₂O)₅Cl]Cl₂ .H₂O
2) [Cr(H₂O)₄Cl₂]Cl.2H₂O
3) [Cr(H₂O)₃Cl₃].3H₂O
4) [Cr(H₂O)₆]Cl₃

Solution:

Answer: (2)

Let x molecule of water are lost then

13.5 = {[x × 18] / [6 × 18 + 3 × 35 + 52]} * 100

x = 1.99 ≃ 2

Question 7: The decreasing order of reactivity of the following compounds towards nucleophilic substitution (S_N2) is:
JEE Main 2020 Solved Paper Chemistry Shift 2 3rd Sept Ques 7

1) (III) > (II) > (IV) > (I)
2) (IV) > (II) > (III) > (I)
3) (II) > (III) > (IV) > (I)
4) (II) > (III) > (I) > (IV)

Solution:

Answer: (3)

Question 8: The increasing order of the reactivity of the following compounds in nucleophilic addition reaction is: Propanal, Benzaldehyde, Propanone, Butanone

1) Benzaldehyde < Propanal < Propanone < Butanone
2) Propanal < Propanone < Butanone < Benzaldehyde
3) Butanone < Propanone < Benzaldehyde < Propanal
4) Benzaldehyde < Butanone < Propanone < Propanal

Solution:

Answer: (3)

Rate of Nucleophilic addition Aldehyde > Ketone Aliphatic aldehyde > Aromatic aldehyde

Question 9: The major product in the following reaction is:
JEE Main 2020 Paper with Solutions Chemistry Shift 2 3rd Sept Q9

Solution:

Answer: (3)

Question 10: The incorrect statement(s) among (a) – (d) regarding acid rain is (are):

(a) It can corrode water pipes.

(b) It can damage structures made up of stone.

(d) It is not harmful for trees

1) (a), (b) and (d)
2) (a), (c) and (d)
3) (c) and (d)
4) (c) only

Solution:

Answer: (3)

Acid rain can cause respiratory ailments in animals and also harmful to trees and plants.

Question 11: 100 mL of 0.1 M HCl is taken in a beaker and to it, 100 mL of 0.1 M NaOH is added in steps of 2 mL and the pH is continuously measured. Which of the following graphs correctly depicts the change in pH?
JEE Main 2020 Paper with Solutions Chemistry Shift 2 3rd Sept Q11

Solution:

Answer: (3)

initially pH will be acidic < 7

at eq pH pH = 7

& finally pH will be basic > 7

Question 12: Consider the hypothetical situation where the azimuthal quantum number, l, takes values 0, 1, 2, ...... n + 1, where n is the principal quantum number. Then, the element with atomic number:

1) 13 has a half-filled valence subshell
2) 9 is the first alkali metal
3) 8 is the first noble gas
4) 6 has a 2p-valence subshell

Solution:

Answer: (1)

(1) ₁₃X = 1s² 1p⁶ 1d⁵ - half filled

(2) ₉X = 1s² 1p⁶ 1d¹ - not alkali metal

(3) ₈X = 1s² 1p⁶ - Second nobel gas

Question 13: The d-electron configuration of [Ru(en)₃]Cl₂ and [Fe(H₂O)₆]Cl₂, respectively are:

1) t⁴_2g e²_g and t⁶_2g e^o_g
2) t⁶_2g e^o_gand t⁶_2g e^o_g
3) t⁴_2g e²_g and t⁴_2g e²_g
4) t⁶_2g e⁰_g and t⁴_2g e²_g

Solution:

Answer: (4)

Question 14: Consider the following molecules and statements related to them:

JEE Main 2020 Solved Paper Chemistry Shift 2 3rd Sept Ques 14

(a) (B) is more likely to be crystalline than (A)

(b) (B) has a higher boiling point than (A)

Identify the correct option from below:

1) (a) and (c) is true
2) only (a) is true (3) (b) and
3) are true
4) (a) and (b) are true

Solution:

Answer: All answers are correct.

Question 15: The strengths of 5.6 volume hydrogen peroxide (of density 1 g/mL) in terms of mass percentage and molarity (M), respectively, are: (Take the molar mass of hydrogen peroxide as 34 g/mol)

1) 0.85 and 0.5
2) 0.85 and 0.25
3) 1.7 and 0.25
4) 1.7 and 0.5

Solution:

Answer: (4)

Volume strength = 5.6V

Molarity = [5.6 / 11.2] = 0.5 mol / l

Mass % = [(0.5 × 34) / (10)] × [(1) / (1g / ml)]

= 1.7%

The answers are 1.7 & 0.5 that is option (4).

Question 16: The compound A in the following reactions is:
JEE Main 2020 Solved Paper Chemistry Shift 2 3rd Sept Ques 16

Solution:

Answer: (1)

Question 17: A mixture of one mole each of H₂, He and O₂ each are enclosed in a cylinder of volume V at temperature T. If the partial pressure of H₂ is 2 atm, the total pressure of the gases in the cylinder is:

1) 6 atm
2) 14 atm
3) 38 atm
4) 22 atm

Solution:

Answer: (1)

p_H2 = 2 atm = xH₂ × p_total

2 atm = [(1) / (1 + 1 + 1] × p_total

p_total= 6 atm

Question 18: Three isomers A, B and C (mol. formula C₈H₁₁N) give the following results:
JEE Main 2020 Solved Paper Chemistry Shift 2 3rd Sept Ques 18

Solution:

Answer: (2)

Question 19: For the reaction 2A + 3B + (3 / 2) C → 3P, which statement is correct?

1) dn_A / dt = dn_B / dt = dn_C / dt
2) dn_A / dt = (3 / 2) dn_B / dt = (3 / 4) dn_C / dt
3) dn_A / dt = (2 / 3) dn_B / dt = (4 / 3) dn_C / dt
4) dn_A / dt = (2 / 3) dn_B / dt = (3 / 4) dn_C / dt

Solution:

Answer: (3)

2A + 3B + (3 / 2) C → 3P

Question 20: Consider the following reaction:

JEE Main 2020 Paper with Solutions Chemistry Shift 2 3rd Sept Q20

The product 'P' gives positive ceric ammonium nitrate test. This is because of the presence of which of these –OH group(s)?

1) (b) only
2) (b) and (d)
3) (c) and (d)
4) (d) only

Solution:

Answer: (1)

Question 21: The volume (in mL) of 0.1 N NaOH required to neutralise 10 mL of 0.1 N phosphinic acid is ___________.

Solution:

Answer: 10 ml

NaOH + H₃ PO₂NaH₂PO₂ + H₂O

Phosphinic

Volume × 0.1 = 0.1 × 10

Volume = 10 ml

Question 22: An acidic solution of dichromate is electrolyzed for 8 minutes using 2A current. As per the following equation

Cr₂O₇^2- + 14H⁺ + 6e^– → 2Cr³⁺+ + 7H₂O

The amount of Cr³⁺ obtained was 0.104 g. The efficiency of the process (in %) is (Take: F = 96000 C, At. mass of chromium = 52) _______.

Solution:

Answer: 60 %

[moles of Cr³⁺] × 3 = [8 × 60 × 2] / 96000

Moles of Cr³⁺= [8 × 4] / 9600 = (1 / 300) mol

Mass of Cr³⁺ = (52 / 300) g

% efficiency = {[Actual obtained amount] / [Theoretical obtained amount]} * 100

= [(0.104 / (52 / 100)) * 100]

= 30 * (104 / 52)

= 60%

Question 23: If 250 cm³ of an aqueous solution containing 0.73 g of a protein A is isotonic with one litre of another aqueous solution containing 1.65 g of a protein B, at 298 K, the ratio of the molecular masses of A and B is ______ × 10^–2 (to the nearest integer).

Solution:

Answer: 177

[0.73 / M_A] × [1000 / 250] = 1.65 / M_B

[M_A / M_B] = [73 × 4] / 165 = 1.769

= 176.9 × 10^–2

= 177 × 10^–2

Question 24: 6.023 × 10²² molecules are present in 10 g of a substance 'x'. The molarity of a solution containing 5 g of substance 'x' in 2 L solution is _____ × 10^–3.

Solution:

Answer: 25

Mol. wt of ‘x’ = {10 / [6.023 × 10²²]} × 6.023 × 10²³

M = [5 / 100] / 2 = [(5 / 200) * 1000] × 10^-3

M = 25 × 10^–3 mol/lit

Question 25: The number of JEE Main 2020 Solved Paper Chemistry Shift 2 3rd Sept Ques 25 groups present in a tripeptide Asp–Glu–Lys is ____.

Solution:

Answer: 5

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