A certain acid–base indicator is red in acid solution and blue in basic solution 75% of the indicator is presentin the solution in its blue form at pH = 5. Calculate the pH at which the indicator shows 90% red form?

(1) 3.56

(2) 5.47

(3) 2.5

(4) 7.4

Subtopic:  Salt Hydrolysis & Titration |
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NEET 2023 - Target Batch - Aryan Raj Singh
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Ionisation constant of HA (weak acid) and BOH (weak base) are 3.0 x 10–7 each at 298K. The percent degree of hydrolysis of BA at the dilution of 10L is :

1. 25

2. 50

3. 75

4. 40

Subtopic:  Salt Hydrolysis & Titration |
 51%
From NCERT
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NEET 2023 - Target Batch - Aryan Raj Singh
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Calculate the molar solubility of zinc tetrathiocyanato–N–mercurate (II) if its Ksp = 2.2 x 10–7.

(1) 0.00380

(2) 0.000469

(3) 0.0095

(4) 0.0183

Subtopic:  Solubility Product |
 72%
From NCERT
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NEET 2023 - Target Batch - Aryan Raj Singh
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To view explanation, please take trial in the course.
NEET 2023 - Target Batch - Aryan Raj Singh

An acid–base indicator which is a weak acid has a pKa value = 5.45. At what cocentration ratio of sodiumacetate to acetic acid would the indicator show a colour half–way between those of its acid and conjugate base forms? pKa of acetic acid = 4.75. [log 2 = 0.3]

(1) 4 : 1

(2) 7 : 1

(3) 5 : 1

(4) 2 : 1

Subtopic:  Buffer |
From NCERT
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NEET 2023 - Target Batch - Aryan Raj Singh
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The indicator constant of phenolphthalein is approximately 10–10. A solution is prepared by adding 100.01c.c. of 0.01 N sodium hydroxide to 100.00 c.c. of 0.01N hydrochloric acid. If a few drops of phenolphthalein are now added, what fraction of the indicator is converted to its coloured form?

(1) 23

(2) 34

(3) 12

(4) 911

Subtopic:  Ionisation Constant of Acid, Base & Salt |
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NEET 2023 - Target Batch - Aryan Raj Singh
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A certain mixture of HCl and CH3 – COOH is 0.1 M in each of the acids. 20 ml of this solution is titrated against 0.1M NaOH. By how many units does the pH change from the start to the stage when the HCl is almost completely neutralised? Ka for acetic acid = 1.8 x 10–6.

(1) 2.03

(2) 0.775

(3) 2.325

(4) 3.172

Subtopic:  pH calculation |
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NEET 2023 - Target Batch - Aryan Raj Singh
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A buffer solution is made by mixing a weak acid HA (Ka = 10–6) with its salt NaA in equal amounts. What should be the amount of acid or salt that should be added to make 90 ml of buffer solution of buffer capacity. 0.1 ?

(1) 10 milli moles

(2) 22 milli moles

(3) 9 milli moles

(4) 11 milli moles

Subtopic:  Buffer |
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NEET 2023 - Target Batch - Aryan Raj Singh
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A sample of water has a hardness expressed as 80 ppm of Ca2+. This sample is passed through an ion exchange column and the Ca2+ is replaced by H+. What is the pH of the water after it has been so treated? [Atomic mass of Ca = 40]

(1) 3

(2) 2.7

(3) 5.4

(4) 2.4

Subtopic:  pH calculation |
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NEET 2023 - Target Batch - Aryan Raj Singh
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In the reaction COCl2(g) CO(g) + CI2(g) at 550° ,Kp = 0.114

,when the initial pressure of CO & Cl2 are 250 and 280 mm of Hg respectively. The equilibrium pressure is found to be 380 mm of Hg. Calculate the degree of dissociation of COCl2 at 1 atm. What will be the extent of dissociation, when N2 at a pressure of 0.4 atm is present and the total pressure is 1 atm.

(1) 0.32 and no change

(2) 0.32 and 0.4

(3) 0.4 and 0.3

(4) at the pressure,N2 dissociation cannot take place

Subtopic:  Kp, Kc & Factors Affecting them |
 64%
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NEET 2023 - Target Batch - Aryan Raj Singh
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What is the value of pKb (CH3COOH) if λm = 390 & λm = 7.8 for 0.04 of a CH3COOH at 25°C

(a) 9.3

(b) 9.2

(c) 4.7

(d) 4.8

Subtopic:  Ionisation Constant of Acid, Base & Salt |
 60%
From NCERT
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NEET 2023 - Target Batch - Aryan Raj Singh
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