MCQ 11 Mark
What is the $p ^{ H }$ of millimolar solution of $NaOH$ ?
- A$13$
- ✓$11$
- C$3$
- D$12$
Answer
View full question & answer→Correct option: B.
$11$
Questions · Page 1 of 3
MCQ
🎯
Test yourself on this topic
50 questions · timed · auto-graded
MCQ 21 Mark
Identify weak acid weak base salt from following.
- ✓Ammonium acetate
- BPotassium bromide
- CAmmonium chloride
- DAmmonium sulphate
Answer
View full question & answer→Correct option: A.
Ammonium acetate
MCQ 31 Mark
An acid dissociated to $1.5 \%$ in it's $0.1 M$ solution. Calculate it's dissociation constant.
- A$1.2 \times 10^{-5}$
- ✓$2.25 \times 10^{-5}$
- C$1.1 \times 10^{-5}$
- D$1.5 \times 10^{-5}$
Answer
View full question & answer→Correct option: B.
$2.25 \times 10^{-5}$
MCQ 41 Mark
What is the $P ^{ H }$ of solution having $H ^{+}$ion concentration $3.981 \times 10^{-7} M$ ? $(\log 3.981=0.6000)$
- A$4.6$
- ✓$6.4$
- C$7.6$
- D$5.6$
Answer
View full question & answer→Correct option: B.
$6.4$
MCQ 51 Mark
Which among the following is NOT Lewis acid?
- ✓$H _2 O$
- B$BF _3$
- C$AlCl _3$
- D$Ag ^{+}$
Answer
View full question & answer→Correct option: A.
$H _2 O$
A
MCQ 61 Mark
What is the $P ^{ H }$ of a $2 \cdot 6 \times 10^{-8} M H ^{+}$ion solution? $(\log 2.6=0.4150)$
- A10.6
- ✓7.6
- C6.5
- D8.4
Answer
View full question & answer→Correct option: B.
7.6
B
MCQ 71 Mark
Identify the conjugate acid-base pair in the following reaction. $H _2 O + HCl \longrightarrow H _3 O ^{+}+ Cl ^{-}$
- A$Cl ^{-}$and $H _2 O$
- B$H _3 O ^{+}$and $Cl ^{-}$
- C$H _2 O$ and $HCl$
- ✓$H _3 O ^{+}$and $H _2 O$
Answer
View full question & answer→Correct option: D.
$H _3 O ^{+}$and $H _2 O$
MCQ 81 Mark
A weak monobasic acid is $2 \%$ dissociated in it's $0.01 M$ solution. What is th dissociation constant of weak acid ?
- ✓$4 \times 10^{-6}$
- B$2.5 \times 10^{-6}$
- C$3 \times 10^{-6}$
- D$2 \times 10^{-6}$
Answer
View full question & answer→Correct option: A.
$4 \times 10^{-6}$
MCQ 91 Mark
The increasing order of $P ^{ H }$ of $0.1 M$ solution of the following compounds is
- ✓$HCl < NH _4 NO _3< NaCl < NaCN$
- B$HCl < NaCl < NaCN < NH _4 NO _3$
- C$NaCN < NaCl < NH _4 NO _3< HCl$
- D$NH _4 NO _3< HCl < NaCl < NaCN$
Answer
View full question & answer→Correct option: A.
$HCl < NH _4 NO _3< NaCl < NaCN$
MCQ 101 Mark
A weak monoacidic base is $1.2 \%$ dissociated in it's $0.2 M$ solution What is the value of dissociation constant?
- A$1.21 \times 10^{-5}$
- ✓$2.88 \times 10^{-5}$
- C$1.44 \times 10^{-5}$
- D$2.54 \times 10^{-5}$
Answer
View full question & answer→Correct option: B.
$2.88 \times 10^{-5}$
MCQ 111 Mark
A solution has $\left[ H ^{+}\right]=0.001 M$. What is the value of $\left[ OH ^{-}\right]$?
- A$10^{-3} M$
- B$10^{-2} M$
- C$1 M$
- ✓$10^{-11} M$
Answer
View full question & answer→Correct option: D.
$10^{-11} M$
MCQ 121 Mark
What is the $p ^{ H }$ at which $Mg ( OH )_2$ starts to precipitate from a solution containing $0.1 M Mg ^{2+}$ ions ? Qxis (Given $K _{ sp }$ for $Mg ( OH )_2=1.0 \times 10^{-11}$ )
- A7
- B4
- C6
- ✓9
Answer
View full question & answer→Correct option: D.
9
D
MCQ 131 Mark
Identify conjugate acid and conjugate base respectively in following reaction. ${ }_0 H _2 O + HCl _{( aq )} \rightleftharpoons H _3 O ^{+}+ Cl ^{-}{ }_{( aq )}$
- A$H _2 O$ and $H _3 O ^{+}$
- B$Cl ^{-}$and $HCl$
- ✓$H _3 O ^{+}$and $H _2 O$
- D$HCl$ and $H _3 O ^{+}$
Answer
View full question & answer→Correct option: C.
$H _3 O ^{+}$and $H _2 O$
MCQ 141 Mark
An organic weak monobasic acid is $0.001$ percent dissociated in it's $0.05 M$ solution. What is it's dissociation constant ?
- A$4 \times 10^{-12}$
- B$1 \times 10^{-12}$
- C$6 \times 10^{-12}$
- ✓$5 \times 10^{-12}$
Answer
View full question & answer→Correct option: D.
$5 \times 10^{-12}$
MCQ 151 Mark
Which among the following salts is formed of strong base and weak acid ?
- A$CuSO _4$
- B$NaNO _3$
- C$NaCl$
- ✓$KCN$
Answer
View full question & answer→Correct option: D.
$KCN$
MCQ 161 Mark
A weak monobasic acid is $2 \%$ dissociated in it's $0.1 M$ solution. What is it's dissociation constant?
- A$2.0 \times 10^{-5}$
- B$2.5 \times 10^{-5}$
- ✓$4.0 \times 10^{-5}$
- D$1.0 \times 10^{-5}$
Answer
View full question & answer→Correct option: C.
$4.0 \times 10^{-5}$
MCQ 171 Mark
What is the $p ^{ H }$ of $2 \times 10^{-3} M$ solution of monoacidic weak base if it ionises to the extent of $5 \%$ ?
- A$14$
- B$6$
- C$4$
- ✓$10$
Answer
View full question & answer→Correct option: D.
$10$
MCQ 181 Mark
Which of the following is a Lewis acid but not a Bronsted acid?
- A$HSO _4^{-}$
- B$HNO _3$
- C$NH _3$
- ✓$BCl _3$
Answer
View full question & answer→Correct option: D.
$BCl _3$
MCQ 191 Mark
Which of the following aqueous solutions of salts will have highest pH value ?
- ✓$Na _2 CO _3$
- B$NH _4 Cl$
- C$NaCl$
- D$CH _3 COONH _4$
Answer
View full question & answer→Correct option: A.
$Na _2 CO _3$
A
MCQ 201 Mark
What is the $p ^{ H }$ of solution containing $H ^{+}$ion concentration $2.5 \times 10^{-3} mol dm ^{-3}$ (given $\log 2.5=0.3979$ )
- ✓2.6
- B3.9
- C3.6
- D$5 \cdot 2$
Answer
View full question & answer→Correct option: A.
2.6
A
MCQ 211 Mark
According to Bronsted- Lowry theory the acids in the following reaction are $ClO _4{ }^{-}+ HCO _3{ }^{-} \longrightarrow HClO _4+ CO _3{ }^{2-}$
- A$HClO _4$ and $CO _3{ }^{2-}$
- B$ClO _4{ }^{-}$and $CO _3{ }^{2-}$
- ✓$HCO _3{ }^{-}$and $HClO _4$
- D$ClO _4{ }^{-}$and $HCO _3{ }^{-}$
Answer
View full question & answer→Correct option: C.
$HCO _3{ }^{-}$and $HClO _4$
MCQ 221 Mark
A centimolar solution of weak acid is $1.3 \%$ dissociated at $298 K$. What is it's dissociation constant?
- A$1.5 \times 10^{-6}$
- B$1.7 \times 10^{-6}$
- ✓$1.3 \times 10^{-6}$
- D$1.9 \times 10^{-6}$
Answer
View full question & answer→Correct option: C.
$1.3 \times 10^{-6}$
MCQ 231 Mark
The percent dissociation of weak monobasic acid is $3 \%$ in it's $0.02 M$ solution. What is the dissociation constant of acid ?
- A$2 \times 10^{-2}$
- B$3 \times 10^{-2}$
- ✓$1.8 \times 10^{-5}$
- D$9 \times 10^{-4}$
Answer
View full question & answer→Correct option: C.
$1.8 \times 10^{-5}$
MCQ 241 Mark
A weak monobasic acid dissociated to $0.001 \%$ in it's $0.01 M$ solution. What is it' dissociation constant?
- A$1 \times 10^{-8}$
- B$1 \times 10^{-6}$
- C$1 \times 10^{-3}$
- ✓$1 \times 10^{-12}$
Answer
View full question & answer→Correct option: D.
$1 \times 10^{-12}$
MCQ 251 Mark
Why the $p ^{ H }$ of aqueous solution of copper sulphate is less than 7 ?
- AIt is a salt of strong acid and strong base.
- BIt is a salt of weak acid and weak base.
- CIt is a salt of weak acid and strong base.
- ✓It is a salt of strong acid and weak base.
Answer
View full question & answer→Correct option: D.
It is a salt of strong acid and weak base.
D
MCQ 261 Mark
A buffer solution is prepared by mixing $0.1 M HCN$ and $0.2 M NaCN$. What is the $p ^{ H }$ of buffer solution if $p ^{ Ka }$ of $HCN$ is 9.3 ?
- A6.15
- B2
- C4.2
- ✓9.6
Answer
View full question & answer→Correct option: D.
9.6
D
MCQ 271 Mark
The $\left[ H ^{+}\right]$in lemon juice is fond to be $0.0063 M$. What is $p ^{ H }$ value of lemon juic $(\log 6.3=0.7993) ?$
- A$5 \cdot 2$
- B$ 2 \cdot 8$
- C$3 \cdot 8$
- ✓$2 \cdot 2$
Answer
View full question & answer→Correct option: D.
$2 \cdot 2$
MCQ 281 Mark
Which among the following is an example of salt of weak acid and strong base
- A$NH _4 CN$
- ✓$KCN$
- C$KCl$
- D${ }_{ } Na _2 SO _4$
Answer
View full question & answer→Correct option: B.
$KCN$
MCQ 291 Mark
For $pH > 7$ the hydronium ion concentration would be
- A$10^{-7} M$
- ✓$<10^{-7} M$
- C$ > 10^{-7} M$
- D$\geq 10^{-7} M$
Answer
View full question & answer→Correct option: B.
$<10^{-7} M$
MCQ 301 Mark
The conjugate base of $\left[ Zn \left( H _2 O \right)_4\right]^{2+}$ is
- A$\left[ Zn \left( H _2 O \right)_4\right]^{2+} NH _3$
- B$\left[ Zn \left( H _2 O \right)_3\right]^{2+}$
- ✓$\left[ Zn \left( H _2 O \right)_3 OH \right]^{+}$
- D$\left[ Zn \left( H _2 O \right) H \right]^{3+}$
Answer
View full question & answer→Correct option: C.
$\left[ Zn \left( H _2 O \right)_3 OH \right]^{+}$
MCQ 311 Mark
Blood in human body is highly buffered at pH of
- ✓7.4
- B7
- C6.9
- D8.1
Answer
View full question & answer→Correct option: A.
7.4
7.4
MCQ 321 Mark
The solubility product of a sparingly soluble salt $A X$ is $5.2 \times 10^{-13}$. Its solubility in $mol dm ^{-3}$ is
- ✓$7.2 \times 10^{-7}$
- B$1.35 \times 10^{-4}$
- C$7.2 \times 10^{-8}$
- D$13.5 \times 10^{-8}$
Answer
View full question & answer→Correct option: A.
$7.2 \times 10^{-7}$
MCQ 331 Mark
Which of the following is a buffer solution ?
- A$CH _3 COONa + NaCl$ in water
- B$CH _3 COOH + HCl$ in water
- ✓$CH _3 COOH + CH _3 COONa$ in water
- D$HCl + NH _4 Cl$ in water
Answer
View full question & answer→Correct option: C.
$CH _3 COOH + CH _3 COONa$ in water
MCQ 341 Mark
Which of the following solution will have pH value equal to 1.0?
- A50 mL of 0.1M HCl + 50mL of 0.1 M NaOH
- B60 mL of 0.1M HCl + 40mL of 0.1 M NaOH
- C20 mL of 0.1M HCl + 80mL of 0.1 M NaOH
- ✓75 mL of 0.2M HCl + 25mL of 0.2 M NaOH
Answer
View full question & answer→Correct option: D.
75 mL of 0.2M HCl + 25mL of 0.2 M NaOH
75 mL of 0.2M HCl + 25mL of 0.2 M NaOH
MCQ 351 Mark
The pH of $10^{-8} M$ of HCl is
- A8
- B7
- ✓less than 7
- Dgreater than 7
Answer
View full question & answer→Correct option: C.
less than 7
less than 7
MCQ 361 Mark
What is the $pH$ of a solution containing $2.2 \times 10^{-6} M$ hydrogen ions?
- A6.34
- ✓5,66
- C4.34
- D3.8
Answer
View full question & answer→Correct option: B.
5,66
(b) : $pH =-\log \left[ H ^{+}\right]$
$pH =-\log \left[2.2 \times 10^{-6}\right]=-\log 2.2+6=-0.342+6=5.66$
$pH =-\log \left[2.2 \times 10^{-6}\right]=-\log 2.2+6=-0.342+6=5.66$
MCQ 371 Mark
Find solubility of $\ce{Pbl_2}$ if it's solubility product is $70 \times 10^{-4}$,
- ✓$1.21 \times 10^{-3} \ce{mol L} ^{-1}$
- B$3.228 \times 10^{-3} \ce{mol L} ^{-1}$
- C$2.831 \times 10^{-3} \ce{mol L} ^{-4}$
- D$1.811 \times 10^{-5} \ce{mol L} ^{-1}$
Answer
View full question & answer→Correct option: A.
$1.21 \times 10^{-3} \ce{mol L} ^{-1}$
$Pbl _2 \rightleftharpoons \underset {S}Pb ^{2+}+ \underset {2S}2 r ^{-}$
Solubility product $=(S)(2 S)^2$
$7.0 \times 10^{-9}=4 S^3 $
$\Rightarrow \frac{7.0 \times 10^{-9}}{4}=S^3$
$S=\sqrt[3]{\frac{7.0 \times 10^{-9}}{4}} $
$\Rightarrow S=1.21 \times 10^{-3} \ce{mol L} ^{-1}$
Solubility product $=(S)(2 S)^2$
$7.0 \times 10^{-9}=4 S^3 $
$\Rightarrow \frac{7.0 \times 10^{-9}}{4}=S^3$
$S=\sqrt[3]{\frac{7.0 \times 10^{-9}}{4}} $
$\Rightarrow S=1.21 \times 10^{-3} \ce{mol L} ^{-1}$
MCQ 381 Mark
Solubility of a salt $A_2 B_3$ is $1 \times 10^{-3} mol dm ^{-3}$. What is the value of its solubility product?
- ✓$1.08 \times 10^{-13}$
- B$8.1 \times 10^{-15}$
- C$2.7 \times 10^{-15}$
- D$2.0 \times 10^{-13}$
Answer
View full question & answer→Correct option: A.
$1.08 \times 10^{-13}$
(a): For $A_2 B_3$, $ A_2 B_3 \longrightarrow \underset {2S}A^{3+}+3 \underset{3S}B^{2-} $
$\begin{aligned}\text { Solubility product } & =(2 S)^2(3 S)^3=108 S^5 \\& =108 \times\left(10^{-3}\right)^5=1.08 \times 10^{-13}\end{aligned}$
$\begin{aligned}\text { Solubility product } & =(2 S)^2(3 S)^3=108 S^5 \\& =108 \times\left(10^{-3}\right)^5=1.08 \times 10^{-13}\end{aligned}$
MCQ 391 Mark
A buffer solution is prepared by mixing $0.2 M$ sodium acetate and $0.1 M$ acetic acid. If $pK_a$, for acetic acid is 4.7. Find the $pH$.
- A
- B
- ✓
- D
Answer
View full question & answer→Correct option: C.
(c) : $pH = p K_a+\log \frac{\text { [Salt] }}{[\text { Acid] }}$
$
pH =4.7+\log \frac{0.2}{0.1}
$
or $pH =4.7+\log 2=4.7+0.3010=5.001$
$
pH =4.7+\log \frac{0.2}{0.1}
$
or $pH =4.7+\log 2=4.7+0.3010=5.001$
MCQ 401 Mark
Which salt from following forms aqueous solution having pH less than 7 ?
- A$CH _3 COONa$
- B$Na _2 SO _4$
- C$CuSO _4$
- D$Na _2 CO _3$
Answer
View full question & answer→(c) : $\mathrm{CH}_3 \mathrm{COONa}$, salt of strong base and weak acid, has $\mathrm{pH}$ of 9.37 .
$\mathrm{Na}_2 \mathrm{SO}_4$, salt of strong acid and strong base, has $\mathrm{pH}$ of 7 .
$\mathrm{Na}_2 \mathrm{CO}_3$, salt of strong base and weak acid, has $\mathrm{pH}$ of $10-11$.
$\mathrm{CuSO}_4$, salt of weak base and strong acid, has acidic $\mathrm{pH}$ of less than 7 .
$\mathrm{Na}_2 \mathrm{SO}_4$, salt of strong acid and strong base, has $\mathrm{pH}$ of 7 .
$\mathrm{Na}_2 \mathrm{CO}_3$, salt of strong base and weak acid, has $\mathrm{pH}$ of $10-11$.
$\mathrm{CuSO}_4$, salt of weak base and strong acid, has acidic $\mathrm{pH}$ of less than 7 .
MCQ 411 Mark
Identify base ${ }_2$ for following equation according to Bronsted-Lowry theory
$\mathrm{HCl}_{(a q)}+\mathrm{H}_2 \mathrm{O}_{(l)} \rightleftharpoons \mathrm{H}_3 \mathrm{O}_{(a q)}^{+}+\mathrm{Cl}_{(a q)}^{-}$
$\mathrm{HCl}_{(a q)}+\mathrm{H}_2 \mathrm{O}_{(l)} \rightleftharpoons \mathrm{H}_3 \mathrm{O}_{(a q)}^{+}+\mathrm{Cl}_{(a q)}^{-}$
- A
- ✓
- C
- D
Answer
View full question & answer→Correct option: B.
(b) : $H _2 O _{l}$ is Bronsted base since it accepts $H ^{+}$ion to form $H _3 O _{\text {(aq) }}^{+}$ .
MCQ 421 Mark
An organic monobasic acid has dissociation constant $2.25 \times 10^{-6}$. What is percent dissociation in it's $0.01 M$ solution?
- ✓$1.5 \%$
- B$15 \%$
- C$5 \%$
- D$0.5 \%$
Answer
View full question & answer→Correct option: A.
$1.5 \%$
(a) : $HA \rightleftharpoons H ^{+}+ A ^{-}$
Given, $K_{ a }=2.25 \times 10^{-5} ; C =0.01 M$
$
K_a=\alpha^2 C
$
$
\alpha=\sqrt{\frac{K_a}{C}}=\sqrt{\frac{2.25 \times 10^{-6}}{0.01}}=1.5 \times 10^{-2}
$
$\%$ dissociation $=\frac{1.5 \times 10^{-2}}{1} \times 100=1.5 \%$
Given, $K_{ a }=2.25 \times 10^{-5} ; C =0.01 M$
$
K_a=\alpha^2 C
$
$
\alpha=\sqrt{\frac{K_a}{C}}=\sqrt{\frac{2.25 \times 10^{-6}}{0.01}}=1.5 \times 10^{-2}
$
$\%$ dissociation $=\frac{1.5 \times 10^{-2}}{1} \times 100=1.5 \%$
MCQ 431 Mark
The solubility product of $PbCl _2$ at $298 K$ is $3.2 \times 10^{-5}$. What is it's solubility in mol $dm ^{-3}$ ?
- A$8 \times 10^{-6}$
- ✓$2 \times 10^{-2}$
- C$5.6 \times 10^{-3}$
- D$5.0 \times 10^{-2}$
Answer
View full question & answer→Correct option: B.
$2 \times 10^{-2}$
$(b) : K_{s p}=3.2 \times 10^{-5}$
$PbCl _2 \rightleftharpoons Pb _S^{2+}+\underset{2 S}{2 Cl ^{-}}$
$K_{s p}=S(2 S)^2$
$3.2 \times 10^{-5}=4 S^3 $
$\Rightarrow 32 \times 10^{-6}=4 S^3$
$S^3=8 \times 10^{-6}$
$S=\sqrt[3]{\left(8 \times 10^{-6}\right)}$
$S=2 \times 10^{-2} \text { moledm }^{-3}$
$PbCl _2 \rightleftharpoons Pb _S^{2+}+\underset{2 S}{2 Cl ^{-}}$
$K_{s p}=S(2 S)^2$
$3.2 \times 10^{-5}=4 S^3 $
$\Rightarrow 32 \times 10^{-6}=4 S^3$
$S^3=8 \times 10^{-6}$
$S=\sqrt[3]{\left(8 \times 10^{-6}\right)}$
$S=2 \times 10^{-2} \text { moledm }^{-3}$
MCQ 441 Mark
Calculate the $pH$ of $0.01 M$ strong dibasic acid.
- A$5.5$
- B$2.5$
- C$2.0$
- ✓$1.7$
Answer
View full question & answer→Correct option: D.
$1.7$
$(d) :$ Let $H _2 A$ be the strong dibasic acid.
$H _2 A \longrightarrow 2 H ^{+}+A^{-}$
$\text {0.01 M } 2 \times 0.01 M$
$\therefore pH =-\log \left[ H ^{+}\right]$
$=-\log [2 \times 0.01]$
$=-\log (0.02)$
$=1.69$
$=1.7$
$H _2 A \longrightarrow 2 H ^{+}+A^{-}$
$\text {0.01 M } 2 \times 0.01 M$
$\therefore pH =-\log \left[ H ^{+}\right]$
$=-\log [2 \times 0.01]$
$=-\log (0.02)$
$=1.69$
$=1.7$
MCQ 451 Mark
Which activity from following is exhibited by Lewis base according to definition?
- Aaccept pair of electron
- ✓donate a pair of electron
- Caccept $H ^{+}$ions
- Ddonate $OH ^{-}$ions
Answer
View full question & answer→Correct option: B.
donate a pair of electron
(b) : Lewis bases are those species which can donate a pair of electrons.
MCQ 461 Mark
Calculate dissociation constant of $0.001 M$ weak monoacidic hase undergoing $2 \%$ dissociation.
- ✓$4 \times 10^{-7}$
- B
- C$2 \times 10^{-7}$
- D$1 \times 10^{-7}$
Answer
View full question & answer→Correct option: A.
$4 \times 10^{-7}$
(a) : We know, dissociation constant $K= C \alpha^2$
where $C=$ molar concentration $=0.001 M$
and $\alpha=$ degree of dissociation $=\frac{2}{100}=0.02$
$
\therefore K=C a^2=0.001 \times(0.02)^2=4 \times 10^{-7}
$
where $C=$ molar concentration $=0.001 M$
and $\alpha=$ degree of dissociation $=\frac{2}{100}=0.02$
$
\therefore K=C a^2=0.001 \times(0.02)^2=4 \times 10^{-7}
$
MCQ 471 Mark
A gas is allowed to expand in an insulated container against a constant external pressure of 2.5 bar from $4.5 dm ^3$ to $7 \times 10^{-3} m ^3$. What is the change in internal energy of the gis?
- A
- B
- C
- D
Answer
View full question & answer→(d) : $\Delta U=q+w$
Since the container is insulated, $q=0$ $ \Delta U=w=-p \Delta V=-p\left(V_2-V_1\right) $
Given: $p=2.5$ bar, $V_2=7 \times 10^{-3} \mathrm{~m}^3=7 \times 10^{-3} \times 10^3 \mathrm{~L}=7 \mathrm{~L}$
$ V_1=4.5 \mathrm{dm}^3=4.5 \mathrm{~L} $
$\begin{aligned} \therefore \Delta U & =-2.5(7-4.5) \mathrm{L} \text { bar }=-6.25 \mathrm{~L} \text { bar } \\ & =-6.25 \times 100 \mathrm{~J}=-625 \mathrm{~J} \quad[\because 1 \mathrm{~L} \text { bar }=100 \mathrm{~J}]\end{aligned}$
Since the container is insulated, $q=0$ $ \Delta U=w=-p \Delta V=-p\left(V_2-V_1\right) $
Given: $p=2.5$ bar, $V_2=7 \times 10^{-3} \mathrm{~m}^3=7 \times 10^{-3} \times 10^3 \mathrm{~L}=7 \mathrm{~L}$
$ V_1=4.5 \mathrm{dm}^3=4.5 \mathrm{~L} $
$\begin{aligned} \therefore \Delta U & =-2.5(7-4.5) \mathrm{L} \text { bar }=-6.25 \mathrm{~L} \text { bar } \\ & =-6.25 \times 100 \mathrm{~J}=-625 \mathrm{~J} \quad[\because 1 \mathrm{~L} \text { bar }=100 \mathrm{~J}]\end{aligned}$
MCQ 481 Mark
What is the $pH$ of millimolar solution of $NaOH$ ?
- A13
- B11
- C3
- D12
Answer
View full question & answer→(b) : One millimolar solution of $\mathrm{NaOH}=1 \times 10^{-3}$ mole/ $\mathrm{L}$ of $\mathrm{NaOH}$
$
\begin{array}{ll}
\therefore & {\left[\mathrm{OH}^{-}\right]=1 \times 10^{-3} \mathrm{~mole} / \mathrm{L}} \\
\therefore & \text { pOH }=-\log \left[\mathrm{OH}^{-}\right]=-\log \left(1 \times 10^{-3}\right)=3 \\
\therefore & \text { pH }=14-3=11
\end{array}
$
$
\begin{array}{ll}
\therefore & {\left[\mathrm{OH}^{-}\right]=1 \times 10^{-3} \mathrm{~mole} / \mathrm{L}} \\
\therefore & \text { pOH }=-\log \left[\mathrm{OH}^{-}\right]=-\log \left(1 \times 10^{-3}\right)=3 \\
\therefore & \text { pH }=14-3=11
\end{array}
$
MCQ 491 Mark
The solubility of product of a sparingly soluble salt $A B_2$ is $3.2 \times 10^{-11}$. If solubility in $mol dm ^{-3}$ is
- A$4 \times 10^{-4}$
- B$3.2 \times 10^{-4}$
- C$1 \times 10^{-5}$
- ✓$2 \times 10^{-4}$
Answer
View full question & answer→Correct option: D.
$2 \times 10^{-4}$
MCQ 501 Mark
$0.1 M HCN$ is dissociated $0.01 \%$. The dissociation constant of $HCN$ is
- A$1.1 \times 10^{-6}$
- B$1 \times 10^{-8}$
- ✓$1 \times 10^{-9}$
- D$1 \times 10^{-7}$
Answer
View full question & answer→Correct option: C.
$1 \times 10^{-9}$