A Physician wishes to prepare a buffer solution at pH =3.58 that efficiently resist changes in pH yet contains only small concentration of the buffering agents. Which one of the following weak acid together with its sodium salt would be best to use ?
m-chlorobenzoic acid (pKa=3.98)
P-Chlorocinnamic acid(pKa = 4.41)
2,5 -dihydroxy benzoic acid (pKa=2.97)
Acetoacetic acid(pKa=3.58)
The pH value of 10 m solution of HCl is_____________
less than 0
Equal to 0
Equal to 1
Equal to 2
A weak acid HA, has a Ka of 1.00 ×10-5. If 0.100 mole of this acid is dissolved in one litre of water, the percentage of acid dissociated at equilibrium is closest to
99.0%
1.00 %
99.9%
0.100%
In which one of the following the solubility of AgCl will be minimum ?
0.1 m NaNO3
Water
0.1 m NaCl
0.1 m NaBr
The compound whose aqueous solution has the highest pH is______________
NaCl
NaHCO3
Na2CO3
NH4 Cl
The hydride ion H- is strong base than its hydroxide ion OH-. Which one of the following reactions will occur if sodium hydride (NaH) is dissolved in Water ?
2H-(aq) + H2O(l)→H2O+H2 +2e-
H-(aq) + H2O(l)→OH-+H2
H - + H2O(l) → no reaction
None of the above
The solubility product of CuS ,CdS and HgS are 10-31 , 10-44 , 10-54 , respectively.The solubility of these sulphides are in the order .
CdS > HgS > CuS
HgS > CdS > CuS
CdS > CuS > HgS
CuS > CdS >HgS
Aqueous solution of acetic acid contains___________
CH3COO- and H+
CH3COO-, H3O+ and CH3COOH
CH3COO-, H3O+ and H+
CH3 COOH, CH3COO- and H+H3COOH
Which of the following statements about pH and H+ ion concentration is incorrect ?
addition of one drop of concentrated HCl in NH4OH solution decreases pH of the solution.
A solution of the mixture of one equivalent of each CH3COOH and NaOH has a pH of 7 .
pH of pure neutral water is not zero .
A cold and con.H2SO4 has lower H+ ion concentration than a diluted solution of H2SO4
Which of the following molecules acts as a Lewis acid ?
(CH3)3B
(CH3)2O
(CH3)3P
(CH3)3N