Which of the following molecules acts as a Lewis acid ?
(CH3)3B
(CH3)2O
(CH3)3P
(CH3)3N
H2S gas when passed through a solution of cations containing HCl precipitates the cations of second group in qualitative analysis but not those belonging to the fourth group. It is because
Presence of HCl decreases the sulphide ion concentration.
Presence of HCl increases the sulphide ion concentration.
Solubility product of group 2nd sulphides is more than that of group iv sulphides
Sulphides of group iv cations are unstable in HCl
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)
Which of the following is most soluble ?
Bi2S3(KSP=1×10-70)
MnS(KSP=7×10-16)
CuS(KSP=8×10-37)
Ag2S(KSP=6×10-51)
Aqueous solution of acetic acid contains
CH3COO- and H+
CH3COO-, H3O+ and CH3COOH
CH3COO-, H3O+ and H+
CH3 COOH, CH3COO- and H+H3COOH
The concentration of [H+] and concentration of [OH- ] of a 0.1M aqueous solution of 2% ionised weak monobasic acid is [ionic product of water = 1×10-14 ]
0.02×10-3 M and 5×10-11 M
1×10-3 M and 3×10-11 M
2×10-3 M and 5×10-12 M
3×10-2 M and 4×10-13 M
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%
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
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 of 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 dilute solution of H2SO4
The pH value of blood does not change appreciably by a small addition of an acid or base ,because the blood
is a body fluid
can be easily coagulated
contains iron as a part of the molecule
contains serum protein that acts as buffer
