The degree of dissociation of water in a 0.1 M aqueous solution of HCl at a certain temperature t°C is 3.6 x 10^–15. The temperature t must be :

(1) < 25°C

(2) = 25°C

(3) > 25°C

(4) insufficient data to predict

Which one is the correct expression below for the solution containing 'n' number of weak acids?

(1) ${\text{[H}}^{+}]=\sqrt{\sum _{i=1}^n\frac{K_i}{C_i}}$

(2) ${\text{[H}}^{+}]=\sqrt{\sum _{i=1}^n{K}_i{C}_i}$

(3) $\left[H^{+}\right]=\sum _{i\hspace{0.17em}=\hspace{0.17em}1}^n{K}_i{C}_i$

(4) none of these

The pH of glycine at the first half equivalence point is 2.34 and that at second half equivalence point is 9.60.At the equivalence point (The first inflection point) The pH is :

(1) 3.63

(2) 2.34

(3) 5.97

(4) 11.94

A 1.458 g of Mg reacts with 80.0 ml of a HCI solution whose pH is –0.477. The change in pH after all Mg has reacted. (Assume constant volume. Mg = 24.3 g/mol.)(log 3 = 0.477)

(1) –0.176

(2) +0.477

(3) –0.2385

(4) 0.3

Find the $∆$pH (initial pH –final pH) when 100 ml 0.01 M HCl is added in a solution containig 0.1 m molesof NaHCO₃ solution (pH = 9 ) of negligible volume ( K_ai =10^–7, K_a, =10^–11 for H₂CO₃) :

(1) 6 + 2 log3

(2) 6 – log3

(3) 6 + 2 Log2

(4) 6 – 2 log3

The ionization constant of benzoic acid is 6.46 x 10^–5 and Kc for silver benzoate is 2.5 x 10^–13. How many times silver benzoate is more soluble in a buffer of pH = 3.19 as compared to its solubility in pure water ?

(1) 3.317

(2) 9.5

(3) 1000

(4) 7.5

30 ml of 0.06 M solution of the protonated form of an anion acid methionine (H₂A⁺) is treated with 0.09 M NaOH. Calculate pH after addition of 20 ml of base.[ pKa₁, = 2.28 and pKa₂ = 9.2.]

1. 5.5

2. 5.74

3. 9.5

4. None of the above

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

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

Calculate the molar solubility of zinc tetrathiocyanato–N–mercurate (II) if its K_sp = 2.2 x 10^–7.

(1) 0.00380

(2) 0.000469

(3) 0.0095

(4) 0.0183