Redox Reactions PYQs Set 5 (PDF)

Set 5 of 6 · Questions 121-150 of 163

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JEE Main Chemistry · Redox Reactions · Set 5 (Q121-150)

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121.
(I) $H_{2} O_{2} + O_{3} \to H_{2} O + 2 O_{2}$
(II) $H_{2} O_{2} + A g_{2} O \to 2 A g + H_{2} O + O_{2}$
Role of hydrogen peroxide in the above reactions is respectively
1. (1) $oxidizing in (I) and reducing in (II)$
2. (2) $reducing in (I) and oxidizing in (II)$
3. (3) $reducing in (I) and (II)$
4. (4) $oxidizing in (I) and (II)$
122.
$2 I O_{3}^{-} + x I^{-} + 12 H^{+} \to 6 I_{2} + 6 H_{2} O$ What is the value of x?
1. (1) $2$
2. (2) $12$
3. (3) $10$
4. (4) $6$
123.
In acidic medium, $H_{2} O_{2}$ changes $C r_{2} O_{7}^{2 -}$ to $C r O_{5}$ which has two $(- O - O -)$ bonds. Oxidation state of Cr in $C r O_{5}$ is
1. (1) $+ 5$
2. (2) $+ 3$
3. (3) $+ 6$
4. (4) $- 10$
124.
Identify the pair of reactions undergoing disproportionation from the following.
1. (1) $2 H_{2} O_{2} \to 2 H_{2} O + O_{2} and Cl_{2} + 2 NaOH \to NaCl + NaOCl + H_{2} O$
2. (2) $P_{4} + 3 NaOH + 3 H_{2} O \to PH_{3} + 3 NaH_{2} PO_{4} and Cl_{2} + 2 NO \to 2 NaCl$
3. (3) $Cl_{2} + 2 KBr \to 2 KCl + Br_{2} and 5 Cl_{2} + I_{2} + 6 H_{2} O \to 2 IO_{3}^{-} + 10 Cl^{-} + 2 H^{+}$
4. (4) $Pb_{3} O_{4} + 8 HCl \to 3 PbCl_{2} + Cl_{2} + H_{2} O and P_{4} + 3 NaOH \to 3 H_{2} O + PH_{3} + 3 NaH_{2} O_{4}$
125.
A mixture of potassium chlorate, oxalic acid and sulphuric acid is heated. During the reaction which element undergoes maximum change in the oxidation number?
1. (1) $S$
2. (2) $H$
3. (3) $Cl$
4. (4) $C$
126.
An example of a disproportionate reaction is:
1. (1) $2 Mn O_{4}^{-} + 10 I^{-} + 16 H^{+} \to 2 M n^{2 +} + 5 I_{2} + 8 H_{2} O$
2. (2) $2 NaBr + C l_{2} \to 2 NaCl + B r_{2}$
3. (3) $2 KMn O_{4} \to K_{2} Mn O_{4} + Mn O_{2} + O_{2}$
4. (4) $2 CuBr \to CuB r_{2} + Cu$
127.
The standard reduction potential at $298 K$ for the following half cell reaction :
$Z n_{(a q)}^{2 +} + 2 e^{-} \to Z n_{(s)}; E^{\circ} = - 0.762 V$
$C r_{(a q)}^{3 +} + 3 e^{-} \to C r_{(s)}; E^{\circ} = - 0.740 V$
$2 H_{(a q)}^{+} + 2 e^{-} \to H_{2 (g)}; E^{\circ} = 0.0 V$
$F_{2 (g)} + 2 e^{-} \to 2 F_{(a q)}^{-}; E^{\circ} = 2.87 V$
Which of the following is the strongest reducing agent?
1. (1) $C r_{(s)}$
2. (2) $Z n_{(s)}$
3. (3) $H_{2 (g)}$
4. (4) $F_{2 (g)}$
128.
0.1 M solution of KI reacts with excess of $H_{2} SO_{4}$ and KIO3 solutions. According to equation
$5 I^{-} + IO_{3}^{-} + 6 H^{+} \to 3 I_{2} + 3 H_{2} O$ Identify the correct statements: (A) 200 mL of KI solution reacts with 0.004 mol of $KIO_{3} (B) 200 mL$ of KI solution reacts with 0.006 mol of $H_{2} SO_{4} (C) 0.5 L$ of KI solution produced 0.005 mol of $I_{2}$ (D) Equivalent weight of KIO3 is equal to ( $\frac{Molecular weight}{5}$ ) Choose the correct answer from the options given below :
1. (1) $(A) and (D) only$
2. (2) $(C) and (D) only$
3. (3) $(B) and (C) only$
4. (4) $(A) and (B) only$
129.
Identify the incorrect statements regarding primary standard of titrimetric analysis.
(A) It should be purely available in dry form.(B) It should not undergo chemical change in air.(C) It should be hygroscopic and should react with another chemical instantaneously and stoichiometrically.(D) It should be readily soluble in water.(E) $KMnO_{4} & NaOH$ can be used as primary standard.
Choose the correct answer from the options given below :
1. (1) $(A) and (B) only$
2. (2) $(C) and (E) only$
3. (3) $(B) and (E) only$
4. (4) $(C) and (D) only$
130.
Given below are two statements:
Statement I: In the oxalic acid vs $KMnO_{4}$ (in the presence of dil $H_{2} SO_{4}$ ) titration the solution needs to be heated initially to $60^{\circ} C$ , but no heating is required in Ferrous ammonium sulphate (FAS) vs $KMnO_{4}$ titration (in the presence of dil $H_{2} SO_{4}$ )
Statement II: In oxalic acid vs $KMnO_{4}$ titration, the initial formation of $MnSO_{4}$ takes place at high temperature, which then acts as catalyst for further reaction. In the case of FAS vs $KMnO_{4}$ , heating oxidizes $Fe^{2 +}$ into $Fe^{3 +}$ by oxygen of air and error may be introduced in the experiment.
choose the correct answer from the options given below
1. (1) $Both Statement I and Statement II are false$
2. (2) $Both Statement I and Statement II are true$
3. (3) $Statement I is false but Statement II is true$
4. (4) $Statement I is true but Statement II is false$
131.
$Match the LIST-I with LIST-II (Redox Reaction) (Type of Redox Reaction)$
$LIST-I$ $LIST-II$
$A. CH_{4 (g)} + 2 O_{2 (g)} \to Δ CO_{2 (g)} + 2 H_{2} O_{(l)}$ $I. Disproportionation reaction$
$B. 2 NaH_{(s)} \to Δ2 Na_{(s)} + H_{2 (g)}$ $II.$
$Combination reaction C. V_{2} O_{5 (s)} + 5 Ca_{(s)} \to Δ2 V_{(s)} + 5 CaO_{(s)} III. Decomposition reaction D. 2 H_{2} O_{2 (aq)} \to Δ H_{2} O_{(l)} + O_{2 (g)} IV. Displacement reaction Choose the correct answer from the options given below:$
1. (1) $A-II, B-III, C-I, D-IV$
2. (2) $A-III, B-IV, C-I, D-II$
3. (3) $A-IV, B-I, C-II, D-III$
4. (4) $A-II, B-III, C-IV, D-I$
132.
Observe the following reaction
$Cl_{2} (g) + 2 OH^{-} (aq) \to ClO^{-} (aq) + Cl^{-} (aq) + H_{2} O (l)$
Identify the correct statements about this reaction
I. $Cl_{2} (g)$ is oxidized to $ClO^{-} (aq)$
II. $Cl_{2} (g)$ is oxidized to $Cl^{-} (aq)$
III. $Cl_{2} (g)$ is reduced to $ClO^{-} (aq)$
IV. $Cl_{2} (g)$ is reduced to $Cl^{-} (aq)$
The correct answer is
1. (1) $I, IV only$
2. (2) $I, III only$
3. (3) $I, II, IV only$
4. (4) $II, III only$
133.
Which of the given reactions is not an example of disproportionation reaction ?
1. (1) $2 H_{2} O_{2} \to 2 H_{2} O + O_{2}$
2. (2) $2 N O_{2} + H_{2} O \to H N O_{3} + H N O_{2}$
3. (3) $M n O_{4}^{-} + 4 H^{+} + 3 e^{-} \to M n O_{2} + 2 H_{2} O$
4. (4) $3 M n O_{4}^{2 -} + 4 H^{+} \to 2 M n O_{4}^{-} + M n O_{2} + 2 H_{2} O$
134.
While titrating dilute $HCI$ solution with aqueous $NaOH$ ,which of the following will not be required?
1. (1) $Pipette and distilled water$
2. (2) $Clamp and phenolphthalein$
3. (3) $Burette and porcelain tile$
4. (4) $Bunsen burner and measuring cylinder$
135.
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : An aqueous solution of KOH when for volumetric analysis, its concentration should be checked before the use.
Reason (R) : On aging, KOH solution absorbs atmospheric $C O_{2}$ .
In the light of the above statements, choose the correct answer from the options given below.
1. (1) $(A) is not correct but (R) is correct$
2. (2) $Both (A) and (R) are correct but (R) is not the correct explanation of (A)$
3. (3) $Both (A) and (R) are correct and (R) is the correct explanation of (A)$
4. (4) $(A) is correct but (R) is not correct$
136.
The value of $E_{1}^{\circ}$ is
1. (1) $0.76 V$
2. (2) $0.535 V$
3. (3) $0.428 V$
4. (4) $1.12 V$
137.
A compound 'X' is a weak acid and it exhibits colour change at pH close to the equivalence point during neutralization of NaOH with $C H_{3}$ COOH.
Compound 'X' exists in ionized form in basic medium. The compound 'X' is :
1. (1) $methyl orange$
2. (2) $methyl red$
3. (3) $phenolphthalein$
4. (4) $erichrome Black T$
138.
Which of the following is not true for oxidation?
1. (1) $Addition of oxygen$
2. (2) $Addition of an electronegative element$
3. (3) $Removal of hydrogen$
4. (4) $Removal of an electronegative element$
139.
The oxidation number of sulphur in $S_{8}$ molecule is
1. (1) $6$
2. (2) $0$
3. (3) $2$
4. (4) $3$
140.
The oxidation state of I in $H_{4} I O_{6}^{-}$ is
1. (1) $+ 1$
2. (2) $- 1$
3. (3) $+ 7$
4. (4) $+ 5$
141.
In the reaction, $2 FeSO_{4} + H_{2} SO_{4} + H_{2} O_{2} \to Fe_{2} (SO_{4})_{3} + 2 H_{2} O$ , the oxidizing agent is
1. (1) $FeSO_{4}$
2. (2) $H_{2} O_{2}$
3. (3) $H_{2} SO_{4}$
4. (4) $both H_{2} SO_{4} and H_{2} O_{2}$
142.
Identify the correct statements :(A) Hydrated salts can be used as primary standard.(B) Primary standard should not undergo any reaction with air.(C) Reactions of primary standard with another substance should be instantaneous and stoichiometric.(D) Primary standard should not be soluble in water.(E) Primary standard should have low relative molar mass.
Choose the correct answer from the options given below:
1. (1) $(A), (B), (C) and (E) Only$
2. (2) $(A) (B) and (E) Only$
3. (3) $(A), (B) and (C) Only$
4. (4) $(D) and (E) Only$
143.
Oxidation state of iron in $Fe (CO)_{4}$ is
1. (1) $+1$
2. (2) $-1$
3. (3) $+2$
4. (4) $0$
144.
Which of the following reactions are disproportionation reaction?
(A) $2 Cu^{+} ⟶ Cu^{2 +} + Cu^{0}$ (B) $3 MnO_{4}^{2 -} + 4 H^{+} ⟶ 2 MnO_{4}^{-} + MnO_{2} + 2 H_{2} O$ (C) $2 KMnO_{4} \to ∆ K_{2} MnO_{4} + MnO_{2} + O_{2}$ (D) $2 MnO_{4}^{-} + 3 Mn^{2 +} + 2 H_{2} O ⟶ 5 MnO_{2} + 4 H^{\oplus}$
Select the correct option from the following
1. (1) $(A) and (B) only$
2. (2) $(A), (B) and (C)$
3. (3) $(A), (C) and (D)$
4. (4) $(A) and (D) only$
145.
The dark purple colour of $K M n O_{4}$ disappears in the titration with oxalic acid in acidic medium. The overall change in the oxidation number of manganese in the reaction is :
1. (1) $5$
2. (2) $1$
3. (3) $7$
4. (4) $2$
146.
$Number of grams of bromine that will completely react with 5.0g of pent-1-ene is______x 1 0^{- 2} g. (Atomic mass of Br = 80 g/mol) [Nearest Integer)$
147.
$KMnO_{4} acts as an oxidising agent in acidic medium. 'X' is the difference between the oxidation states of Mn in reactant and product. 'Y' is the number of 'd' electrons present in the brown red precipitate formed at the end of the acetate ion test with neutral ferric chloride. The value of X + Y is .$
148.
$Potassium chlorate is prepared by the electrolysis of KCl in basic solution 6 OH^{-} + Cl^{-} \to ClO_{3}^{-} + 3 H_{2} O + 6 e^{-} If only 60 % of the current is utilized in the reaction, the time (rounded to the nearest hour) required to produce 10 g of KClO_{3} using a current of 2 A is (Given: F = 96, 500 Cmol^{- 1} molar mass of KClO_{3} = 122 gmol^{- 1})$
149.
$Some CO_{2} gas was kept in a sealed container at a pressure of 1 atm and at 273 K. This entire amount of CO_{2} gas was later passed through an aqueous solution of Ca (OH)_{2} . The excess unreacted Ca (OH)_{2} was later neutralized with 0.1 M of 40 mL HCl. If the volume of the sealed container of CO_{2} was x, then x is cm^{3} (nearest integer). [Given: The entire amount of CO_{2} (g) reacted with exactly half the initial amount of Ca (OH)_{2} present in the aqueous solution.]$
150.
$10.0 ml of Na_{2} CO_{3} solution is titrated against 0.2 MHCl solution. The following titre values were obtained in 5 readings. 4.8 ml, 4.9 ml, 5.0 ml, 5.0 ml and 5.0 ml Based on these readings, and convention of titrimetric estimation ofconcentration of Na_{2} CO_{3} solution is________mM (Round off to the Nearest integer)$