The hydrogen ion concentration of a 10$$-$$8 M, HCl aqueous solution at 298 K (Kw = 10$$-$$14) is
A
1.0 $$ \times $$ 10$$-$$8 M
B
1.0 $$ \times $$ 10$$-$$6 M
C
1.0525 $$ \times $$ 10$$-$$7 M
D
9.525 $$ \times $$ 10$$-$$8 M
Explanation
In HCl solution [H+] = 10-8 M
Also from water, [H+] = 10-7 M
$$ \therefore $$ Total [H+] = 10-8 M + 10-7 M
= 1.1 ×10–7 M
$$ \simeq $$ 1.0525 $$ \times $$ 10$$-$$7 M
2
MCQ (Single Correct Answer)
AIPMT 2006
Which of the following pairs constitutes a buffer?
A
HCl and KCl
B
HNO2 and NaNO2
C
NaOH and NaCl
D
HNO3 and NH4NO3
Explanation
HNO2 is a weak acid and NaNO2 is its salt
thus these two constitute to form an acidic buffer.
3
MCQ (Single Correct Answer)
AIPMT 2006
For the reaction :
CH4(g) + 2O2(g) $$\rightleftharpoons$$ CO2(g) + 2H2O(l),
$$\Delta $$Hr = $$-$$ 170.8 kJ mol$$-$$1.
Which of the following statements is not true?
A
The reaction is exothermic.
B
At equilibrium, the concentrations of CO2(g) and H2O(l) are not equal.
C
The equilibrium constant for the reaction is given by Kp = $${{\left[ {C{O_2}} \right]} \over {\left[ {C{H_4}} \right]\left[ {{O_2}} \right]}}$$
D
Addition of CH4(g) or O2(g) at equilibrium will cause a shift to the right.
Explanation
Option C is incorrect as the value of KP
given is wrong. It should have been
