Free NEET Chemistry multiple-choice questions on pH & Buffer Solutions. Attempt each question and reveal the answer with a full explanation.
Buffer capacity of a buffer solution is maximum when: [Salt] = [Acid] [Salt] = 10 [Acid] [Acid] = 10 [Salt] pH = 7 Buffer capacity is maximum when: [Salt] = [Acid] [Salt] = 10 [Acid] [Acid] = 10 [Salt] pH = 7 What is the pH of a 0.001 M HCl solution? 3 2 4 1 What is the pH of a 0.02 M Ba(OH) 2 solution assuming complete ionization? 12.60 1.40 12.30 11.70 Buffer capacity is defined as the number of moles of acid or base added to one litre of buffer to change its pH by: 1 unit 0.1 unit 7 units 0.01 unit What is the pH of a 0.05 M Ba(OH) 2 solution? 13.0 12.7 1.0 13.3 Calculate the pH of a solution containing 0.1 M CH 3COOH and 0.1 M CH 3COONa (Given pK a of CH 3COOH = 4.76 ): 4.76 3.76 5.76 7.00 What is the pH of a 0.01 M NaOH solution? 12 2 10 7 What is the pH of a solution formed by mixing 100 mL of 0.1 M HCl and 100 mL of 0.1 M NaOH ? 7.0 1.0 13.0 0.0 Which of the following mixtures acts as an acidic buffer? CH 3COOH + CH 3COONa NH 4OH + NH 4Cl NaOH + NaCl HCl + KCl Which of the following pairs constitutes a buffer:- HNO2 & NaNO2 NaOH & NaCl HNO3 & NH4NO3 HCl & KCl The pH of a buffer solution remains almost constant upon addition of small amounts of acid or base because: The added H + or OH - ions react with the buffer components to form weak electrolytes. The buffer solution is a very strong acid. The buffer components are completely ionized. The ionic product of water remains constant. Calculate the pOH of a solution at 25 C that contains 1 10 -10 M of hydrouium ions, i.e. H3O+ . 4.000 9.0000 1.000 7.000 The pH of the solution containing 50 mL each of 0.10 M sodium acetate and 0.01 M acetic acid is [Given pK a of CH3COOH = 4.57] 3.57 4.57 2.57 5.57 At 298 K, a certain buffer solution contains equal concentrations of X - and HX . K b for X - is 10 -10 . What is the pH of this buffer solution? 10 4 2 6 The pH of a 10 -8 M solution of HCl is: Between 6 and 7 8 7 Between 7 and 8 A buffer solution is prepared by mixing 0.1 M acetic acid and 0.1 M sodium acetate. If K a for acetic acid is 1.8 10 -5 , the pH of the buffer is: 4.74 3.74 5.74 7.00 What is the pH of a solution formed by mixing 40 mL of 0.1 M HCl with 10 mL of 0.45 M NaOH ? 12 10 8 2 Which of the following will have the highest pH? 0.1 M Na 2CO 3 0.1 M NaCl 0.1 M NH 4Cl 0.1 M HCl The pH of a 0.1 M solution of a weak monoacidic base is 11. The dissociation constant K b of the base is: 10 -5 10 -3 10 -11 10 -6 What is the pH of a 0.01 M Ca(OH) 2 solution assuming complete ionization? 12.30 12.00 2.00 11.70 Calculate the pH of a 10 -3 M H 2SO 4 solution (assuming both protons dissociate completely). 2.70 3.00 2.00 1.70 Which of the following buffers is formed by a weak acid and its salt with a strong base? CH 3COOH + CH 3COONa NH 4OH + NH 4Cl HCl + NaCl NaOH + NaCl The pH of a 1.0 10 -7 M solution of HCl is approximately: 6.79 7.00 7.10 8.00 The pK a of a weak acid HA is 4.80 . The pK b of a weak base BOH is 4.78 . The pH of an aqueous solution of the salt BA will be: 7.01 4.79 9.22 6.50 What is the concentration of OH - ions in a solution with a pH of 4.3 ? 2.0 10 -10 M 5.0 10 -5 M 1.0 10 -10 M 2.0 10 -4 M The pH of blood is maintained by the carbonic acid-bicarbonate buffer. If the ratio of [HCO 3 -]/[H 2CO 3] in blood is 20 , and pK a of H 2CO 3 is 6.1 , the pH of blood is: 7.4 6.1 8.1 7.0 At 373 K , the K w of water is 1 10 -12 . The pH of pure water at this temperature will be: 6 7 12 0 The pH of 0.1 M NH 4Cl solution is (Given pK b of NH 4OH = 4.75 ): 5.12 9.25 7.00 4.75 The indicator phenolphthalein shows a color change in the pH range of: 8.3 - 10.0 3.1 - 4.4 4.2 - 6.3 1.2 - 2.8 If the ionic product of water K w is 5.44 10 -14 at 50 C , the pH of a neutral solution at this temperature is: 6.63 7.00 7.37 6.00 Which of the following mixtures will act as an acidic buffer solution? 100 mL of 0.1 M CH 3COOH + 50 mL of 0.1 M NaOH 100 mL of 0.1 M NaOH + 100 mL of 0.1 M HCl 50 mL of 0.1 M CH 3COOH + 100 mL of 0.1 M NaOH 100 mL of 0.1 M NH 4OH + 50 mL of 0.1 M HCl The ionic product of water ( K w ) at 60 C is 9.6 10 -14 . What is the pH of neutral water at this temperature? 6.51 7.00 6.00 7.49 At 90 ∘C , pure water has [H 3O +] = 10 -6 mol L -1 . What is the value of K w at this temperature? 10 -12 10 -14 10 -6 10 -7 In a titration of a weak acid ( HA ) with a strong base ( NaOH ), the pH at the half-equivalence point is: Equal to pK a Equal to 7 Greater than pK a Less than pK a What is the pH of a 0.1 M solution of ammonium acetate ( CH 3COONH 4 )? Given pK a of CH 3COOH = 4.76 and pK b of NH 4OH = 4.75 at 25 C . 7.005 7.000 6.995 4.755 The pH of a solution formed by mixing 50 mL of 0.01 M Ba(OH) 2 with 50 mL of water is: 12.00 11.70 2.00 12.30 The value of K w at 25 C is 10 -14 . If the temperature is increased to 60 C , the pH of neutral water will be: Less than 7 Greater than 7 Equal to 7 Exactly 14 In the titration of CH 3COOH with NaOH , which of the following indicators is the most suitable? Phenolphthalein Methyl orange Methyl red Bromocresol green The hydrogen ion concentration of a 10 -8 M HCl aqueous solution at 298 K ( K w = 10 -14 ) is:- 1.0 10 -6 M 1.0525 10 -7 M 9.525 10 -8 M 1.0 10 -8 M Following solutions were prepared by mixing different volumes of NaOH and HCl of different concentrations : a. 60 mL M 10 HCl + 40 mL M 10 NaOH b. 55 mL M 10 HCl + 45 mL M 10 NaOH c. 75 mL M 5 HCl + 25 mL M 5 NaOH d. 100 mL M 10 HCl + 100 mL M 10 NaOH pH of which one of them will be equal to 1? d a b c Which will make basic buffer? 100 mL of 0.1 M HCl + 100 mL of 0.1 M NaOH 50 mL of 0.1 M NaOH + 25 mL of 0.1 M CH3COOH 100 mL of 0.1 M CH3COOH + 100 mL of 0.1 M NaOH 100 mL of 0.1 M HCl + 200 mL of 0.1 M NH4OH The p K b of dimethylamine and p K a of acetic acid are 3.27 and 4.77 respectively at T (K). The correct option for the pH of dimethylammonium acetate solution is : 5.50 7.75 6.25 8.50 What is the pH of a solution made by mixing equal volumes of 0.1 M HCl and 0.1 M CH 3COONa ? ( pK a for CH 3COOH = 4.74 ) 2.87 4.74 1.00 7.00 The pH of a buffer solution containing 0.1 M of a weak acid HA ( pK a = 4.75 ) and 0.1 M of its salt MA is: 4.75 3.75 5.75 7.00 The pH of a 0.1 M solution of sodium acetate ( CH 3COONa ) is (given pK a of CH 3COOH = 4.74 ): 8.87 7.00 5.13 9.26 The pH of a buffer solution containing equal concentrations of B - and HB ( K b for B - = 10 -10 ) is: 4 10 7 6 What is the pH of a 10 -7 M NaOH solution at 25 C (taking water's dissociation into account)? 7.21 7.00 6.79 8.00 At 37 C (human body temperature), the ionic product of water K w is 2.4 10 -14 . The pH of neutral water at this temperature is approximately: 6.8 7.0 7.2 6.0 The pH of a 0.01 M solution of sodium acetate ( CH 3 COONa ) is (Given pK a of acetic acid = 4.74): 8.37 5.63 7.00 9.37 What is the pH of a solution obtained by mixing 50 mL of 0.1 M NaOH with 50 mL of 0.1 M CH 3 COOH ? ( pK a of CH 3 COOH = 4.74 ) 8.72 7.00 4.74 9.26 A buffer solution is formed by mixing equal volumes of 0.2 M NH 4OH and 0.1 M HCl . If pK b of NH 4OH is 4.75 , the pH of the resulting solution is: 9.25 4.75 8.25 5.75 What is the pH of a 10 -9 M aqueous solution of NaOH at 25 C ? Approximately 7.0 Exactly 9.0 Exactly 5.0 Approximately 8.0 The dissociation constant of a weak acid HA is 4.9 10 -8 . After adding 10 mL of 0.1 M NaOH to 20 mL of 0.1 M HA , the pH of the resulting solution is: 7.31 4.75 9.25 8.12 The pH of 0.1 M aqueous solution of NH 4CN ( pK a of HCN = 9.2 , pK b of NH 3 = 4.75 ) is: 9.225 7.000 4.750 8.125 Calculate the pH of 0.0005 M H 2SO 4 solution (assuming complete dissociation). 3.0 4.0 3.3 2.7 Calculate the pH of a 0.1 M solution of sodium cyanide ( NaCN ). (Given K a for HCN = 4 10 -10 and K w = 10 -14 at 25 C ) 11.20 2.80 5.20 8.80 Calculate the pH of a 10 -10 M solution of NaOH at 25 C . 7.00 4.00 10.00 6.00 At 25 C , the K w of water is 10 -14 . What is the value of pK a for pure water? 15.74 14.00 7.00 1.00 Which buffer system is responsible for maintaining the pH of human blood between 7.35 and 7.45? H 2CO 3 / HCO 3 - NH 4OH / NH 4Cl CH 3COOH / CH 3COONa HCl / NaCl The dissociation constant of a weak acid HA is 1 10 -5 . The pH of 0.1 M solution of this acid will be: 3 5 1 2 In an acidic buffer solution, if the concentration of the salt is 10 times the concentration of the acid, the pH of the solution will be: pK a + 1 pK a - 1 pK a 10 pK a