pH the Power of H

Q. Ammonium hydroxide is a weak base because:

1. It has low vapour pressure
2. It has low density
3. It is only slightly ionized
4. It is not a hydroxide of any metal

Q. Calculate pH of $0.002NN{H}_{4}OH$ having 2 % dissociation.

1. 7.6
2. 8.6
3. 9.6
4. 10.6

Q. The value of $p{K}_w$ of water will :

1. Increases with increase in temperature
2. Decreases with increase in temperature
3. Does not change with variation in temperature
4. Increase till $50{}^{o}C$ temperature and there after decreases.

Q. $K_b$ values for the aqueous methylamine, ammonia, urea and pyridine are: $5.6\times {10}^{-4}$, $1.8\times {10}^{-5}$, $1.5\times {10}^{-14}$ and $1.7\times {10}^{-9}$ respectively.
Which is the correct order of basic strength?

1. Methylamine > Ammonia > Urea > Pyridine
2. Methylamine < Ammonia < Urea < Pyridine
3. Methylamine > Ammonia > Pyridine > Urea
4. Methylamine < Ammonia < Pyridine < Urea

Q. A buffer solution of $pH=4$ is to be prepared, using $C{H}_{3}COOH$ and $C{H}_{3}COONa.$ The concentration of acetic acid and sodium acetate are $\frac{1}{10}M$ and $xM$. How much will the $pH$ be if $1.5L$ of $H_{2}O$ is added to above buffer ? $K_a\left(C{H}_{3}COOH\right)=4.7447$

1. $4$
2. $6$
3. $8$
4. $2$

Q. Which of the following options is/are correct regarding the colour of phenolphthalein and methyl orange in acidic and basic medium?

1. Phenolphthalein:
   Colour in acidic solution: Colourless
   Colour in basic solution: Pink
2. Methyl orange:
   Colour in acidic solution: Yellow
   Colour in basic solution: Red
3. Phenolphthalein:
   Colour in acidic solution: Pink
   Colour in basic solution: Colourless

4. Methyl orange:
   Colour in acidic solution: Red
   Colour in basic solution: Yellow

Q. 100 mL of 0.005 M $H_{2}S{O}_4$ is diluted to 1 L. The resulting pH will be .

1. 3
2. 5
3. 4

Q. $10\text{mL}$ of $\frac{\text{M}}{200}{H}_{2}S{O}_4$ is mixed with $40\text{mL}$ of $\frac{\text{M}}{200}{H}_{2}S{O}_4$. The pH of resulting solution is:

1. $2.301$
2. $1.301$
3. $2$
4. $1$

Q.

What will be the sum of pH and pOH​ in an aqueous solution?

1. 7

2. $p{K}_w$

3. Zero

4. 1

Q. Calculate the pH of the solution formed by mixing equal volume of two solutions of $pH=3$ and $pH=4$ repectively ?
( log 5.5 = 0.740 )

1. 7
2. 4.26
3. 5.26
4. 3.26

Q. For a neutral solution which one is correct ?

1. $O{H}^{-}$ ions are not present.
2. Both $H_3{O}^{+}$ and $O{H}^{-}$ ions are not present.
3. Both $H_3{O}^{+}$ and $O{H}^{-}$ ions are present in small but equal concentration.
4. $H_3{O}^{+}$ ions are not present.

Q. Which of the following is the strongest base? ($K_b$ values at $25{}^{0}C$)

1. Fluoride ion: $K_b=1.4\times {10}^{-11}$
2. Ammonia : $K_b=1.8\times {10}^{-5}$
3. Hydrazine : $K_b=9.5\times {10}^{-7}$
4. Aniline : $K_b=4.3\times {10}^{-10}$

Q. Two weak monobasic acids HA and HB having equal concentrations of 0.5 M are present in solution at ${25}^{o}C$ having dissociation constants as $3.5\times {10}^{-10}$ and $4.5\times {10}^{-10}$ respectively. Calculate the pH of the solution at given temperature.

1. 4.7
2. 5.7
3. 6.7
4. 2.5

Q. Which of the following is the correct option regarding $K_{a_1}$ for the first dissociation and $K_{a_2}$ for the second dissociation of a polyprotic acid ?

1. $K_{a_1}$ has more value than $K_{a_2}$
2. $K_{a_1}$ has less value than $K_{a_2}$
3. $K_{a_1}$ has value equal to $K_{a_2}$
4. None of the above

Q.

The pH of a solution is enhanced from 2 to 3. The concentration of H⁺ in the new solution

1. is three times the original solution

2. is about 1.5 times the original solution

3. decreases to a tenth

4. increases 10 times

Q. What is the correct relationship between the pHs of isomolar solutions of sodium oxide $\left(p{H}_1\right),$ sodium sulphide $\left(p{H}_2\right),$ sodium selenide $p{H}_3)$ and sodium telluride $p{H}_4)$ ?

1. $p{H}_1>p{H}_2\approx p{H}_3>p{H}_4$
2. $p{H}_1<p{H}_2<p{H}_3<p{H}_4$
3. $p{H}_1<p{H}_2<p{H}_3\approx p{H}_4$
4. $p{H}_1>p{H}_2>p{H}_3>p{H}_4$

Q. Calculate the pH of a buffer solution made from 0.20 $MH{C}_2{H}_3{O}_2$ and 0.50 M $C_2{H}_3{O}_2^{-}$ that has an acid dissociation constant for $H{C}_2{H}_3{O}_2$ of $1.8\times {10}^{-5}.$
log(1.8 )=0.255, log(2.5 )=0.397

1. 7
2. 5.14
3. 5.64
4. 4.35

Q. Calculate the molar concentration of a solution of acetic acid (HOAc) that has a pH of $4.00(K_a=1.8\times {10}^{-5})$

1. $1.0\times {10}^{-3}$
2. $1.0\times {10}^{-6}$
3. $5.56\times {10}^{-4}$
4. $3.0\times {10}^{-2}$

Q. 9.125 g of $HCl$ is present in 0.5 L of solution at ${25}^{\circ }C$. The pH of the solution is :

1. 1.44
2. 0.88
3. 0.6
4. 0.3

Q. The following solutions were prepared by mixing different volumes of NaOH and HCl of different concentrations
1. 60 mL $\frac{M}{10}$ HCl + 40 mL $\frac{M}{10}$ NaOH

2. 55 mL $\frac{M}{10}$ HCl + 45 mL $\frac{M}{10}$ NaOH

3. 75 mL $\frac{M}{5}$ HCl + 25 mL $\frac{M}{5}$ NaOH

4. 100 mL $\frac{M}{10}$ HCl + 100 mL $\frac{M}{10}$ NaOH

pH of which one of them will be equal to 1?

1. 1
2. 2
3. 3
4. 4

Q. Find moles of $N{H}_{4}Cl$ required to prevent $Mg(OH{)}_2$ from precipitating in a litre of solution which contains 0.02 mole of $N{H}_3$ and 0.001 mole of $M{g}^{2+}$ ions.
Given : $K_b\left(N{H}_3\right)={10}^{-5};K_{sp}\left[Mg\right(OH{)}_2]={10}^{-11}$

1. ${10}^{-4}$
2. $2\times {10}^{-3}$
3. $0.02$
4. $0.1$

Q.

Which of the following solution will have a pH exactly equal to 9 ?

1. ${10}^{-9}MHCl\text{solution at}{25}^{0}C$
2. $2\times {10}^{-3}MBa(OH{)}_2\text{solution at}{25}^{0}C$
3. ${10}^{-9}MNaOH\text{solution at}{25}^{0}C$
4. None of the above

Q. Calculate the $pH$ of a $0.05M$ weak monobasic acid solution. The value of dissociation constant is $8.0\times {10}^{-9}$.

1. 2
2. 4.69
3. 6.6
4. 6.37

Q. What is the pH of $1.5L$ of vinegar that is 3% acetic acid by mass ? $(K_a=1.8\times {10}^{-5})$

1. 12
2. 7
3. 4.3
4. 2.5

Q. Calculate the pH of the solution formed by mixing equal volume of two solutions A and B at $25{}^{o}C$ having $pH=10$ and $pH=12$ repectively ?
(Given log (5.05) = 0.703)

1. 11.7
2. 10.29
3. 12
4. None of the above

Q. The dissociation constant of $0.01MC{H}_{3}COOH$ is $1.8\times {10}^{-5}$ then calculate $C{H}_{3}CO{O}^{-}$ concentration in 0.1 M $HCl$ solution.

1. $1.8\times {10}^{-6}mol{L}^{-1}$
2. $1.8\times {10}^{-8}mol{L}^{-1}$
3. $3.8\times {10}^{-6}mol{L}^{-1}$
4. $3.8\times {10}^{-8}mol{L}^{-1}$

Q. What is the minimum $pH$ required to prevent the precipitation of $ZnS$ in a solution that is $0.01$ $MZnC{l}_2$ and saturated with $0.10M{H}_{2}S$?
[Given : $K_{sp}={10}^{-21},K_{a_1}\times K_{a_2}={10}^{-20}]$

1. \N
2. 1
3. 2
4. 4

Q.

For a neutral solution which of the following statement(s) is/are correct ?

1. The molar concentration of $H_3{O}^{+}={10}^{-7}$ at $298K$..
2. The molar concentration of $O{H}^{-}={10}^{-7}$ at $298K$..
3. Both $H_3{O}^{+}$ and $O{H}^{-}$ ions are not present.
4. Both $H_3{O}^{+}$ and $O{H}^{-}$ ions are present in small but equal concentration.

Q. 100 mL of 0.005 M $H_{2}S{O}_4$ is diluted to 1 L. The resulting pH will be .

1. 3
2. 5
3. 4

Q. Calculate the pH of $0.01MN{H}_{4}OH$ solution having 2% dissociation.

1. 7.3
2. 10.3
3. 8.3
4. 12.3