Question 11 Mark
Predict if solutions of following salts are neutral, acidic or basic :
$NaCl , KBr , NaCN , NH _4 NO _3, NaNO _2$ and KF .
Answer| Neutral solution | $NaCl , KBr$ (Salt of strong acid and strong base) |
| Acidic solution | $NH _4 NO _3$ (Salt of strong acid $HNO _3$ and weak base $\left.NH _4 OH \right)$ |
| Basic solution | $NaCN , NaNO _2, KF$ (Salt of weak acid and strong base) |
View full question & answer→Question 21 Mark
For the following equilibrium, $K_c=6.3 \times$ $10^{14}$ at 1000 K
$NO ( g )+ O _3(g) \rightleftharpoons NO _2(g)+ O _2(g)$
Both the forward and reverse reactions in the equilibrium are elementary bimolecular reactions. What is $K_c$, for the reverse reaction?
AnswerEquilibrium constant for backward reaction :
$K _{ c }^{\prime}=\frac{1}{K_{ c }}=\frac{1}{6.3 \times 10^{14}}=1.587 \times 10^{-15}$
$=1.59 \times 10^{-15}$
$K _{ c }^{\prime}=1.59 \times 10^{-15}$
View full question & answer→Question 31 Mark
The pH of a sample of vinegar is 3.76 . Calculate the concentration of hydrogen ion in it.
Answer$\log \left[ H ^{+}\right]=- pH$
$\begin{array}{l}=-3.76 \\ =\overline{4} .24\end{array}$
$\left[ H ^{+}\right]=$Antilog $\overline{4} .24$ (Antilog $\left.0.24=1738\right)$
$\left[ H ^{+}\right]=1.738 \times 10^{-4} M$
View full question & answer→Question 41 Mark
The concentration of hydrogen ion in a sample of soft drink is $3.8 \times 10^{-3} M$. What is its pH ?
Answer$pH =-\log \left[ H ^{+}\right]$
$\left[ H ^{+}\right]=3.8 \times 10^{-3}$
Hence $pH =-\log \left(3.8 \times 10^{-3}\right)$
$pH =-\log 3.8-\log 10^{-3}$
$pH =-0.5798+3 \quad(\log 3.8=0.5798)$
$\begin{array}{l} pH =2.4202 \\ pH =2.42\end{array}$
View full question & answer→Question 51 Mark
Write conjugate acids for following bronsted bases : $NH _2^{-}, NH _3$ and $HCOO ^{-}$.
Answer| Bronsted bases | Bronsted acids |
| $NH _2^{-}$ | $NH _3$ |
| $NH _3$ | $NH _4^{+}$ |
| $HCOO ^{-}$ | HCOOH |
View full question & answer→Question 61 Mark
What will be conjugate bases for the Bronsted acids : $HF , H _2 SO _4$ and $HCO _3^{-}$?
Answer| Bronsted acids | Bronsted bases |
| HF | $F ^{-}$ |
| $H _2 SO _4$ | $HSO _4^{-}$ |
| $HCO _3^{-}$ | $CO _3^{2-}$ |
View full question & answer→Question 71 Mark
Which of the followings are Lewis acids? $H _{ 2 } O , B F _{ 3 }, H ^{+}$, and $N H _4^{+}$.
Answer$BF _3, H ^{+}, NH _4^{+}$(Here $NH _4^{+}$is very weak Lewis acid).
View full question & answer→Question 81 Mark
Predict which of the following reaction will have appreciable concentration of reactants and products :
(a) $Cl _2(g) \rightleftharpoons 2 Cl ( g ) K _{ c }=5 \times 10^{-39}$
(b) $Cl _2(g)+2 NO ( g ) \rightleftharpoons 2 NOCl ( g ) K _{ c }=3.7 \times 10^8$
(c) $Cl _2(g)+2 NO _2(g) \rightleftharpoons 2 NO _2 Cl ( g ) K _c=1.8$
AnswerIn reaction (c) value of $K_c$ is not so much high not so much less. Hence in this at equilibrium the concentration of reactants and products will be comparable. In reaction (a) $K_c$ is very less and in (b) it is very high.
View full question & answer→Question 91 Mark
What is $K_c$ for the following equilibrium when the equilibrium concentration of each substance is : $\left[ SO _2\right]=0.60 M ,\left[ O _2\right]=0.82 M$ and $\left[ SO _3\right]=1.90 M$ ?
$2 SO _2(g)+ O _2(g) \rightleftharpoons 2 SO _3(g)$
AnswerFor reaction
$
2 SO_2(g)+O_2(g) \rightleftharpoons 2 SO_3(g)
$
$K _{ c }=\frac{\left[ SO _3\right]^2}{\left[ SO _2\right]^2\left[ O _2\right]}=\frac{(1.90)^2}{(0.60)^2(0.82)}$
$=12.22899=12.229 mol L ^{-1}$
$K _{ c }=12.229 mol L ^{-1}$
View full question & answer→Question 101 Mark
The equilibrium constant expression for a gas reaction is,
$K _{ c }=\frac{\left[ NH _3\right]^4\left[ O _2\right]^5}{[ NO ]^4\left[ H _2 O \right]^6}$
Write the balanced chemical equation corresponding to this expression.
Answer$4 NO ( g )+6 H _2 O ( g ) \rightleftharpoons 4 NH _3(g)+5 O _2(g)$
View full question & answer→Question 111 Mark
Write relationship between $K_a, K_w$ and $K_n$ for KCN .
Answer$K _{ h }=\frac{ K _{ w }}{ K _{ a }}$ (Salt of weak acid and strong base).
View full question & answer→Question 121 Mark
What will be the effect on ionisation of $H _2 S$ in presence of HCl ?
Answer $H _2 S$ is a weak acid. Hence in presence of HCl (weak acid), due to common ion effect, ionization of $H _2 S$ get suppressed.
View full question & answer→Question 131 Mark
State the nature of aqueous solution of $Na _2 CO _3$.
Answer $Na _2 CO _3$ is a salt of weak acid $\left( H _2 CO _3\right)$ and strong base $( NaOH )$. Hence its aqueous solution will be be bic.
View full question & answer→Question 141 Mark
Write the solubility product expression for silver chromate $\left( Ag _2 CrO _4\right)$
AnswerSolubility product $\left( K _{ sp }\right)=\left[ Ag ^{+}\right]^2\left[ CrO _4^{-2}\right]$
View full question & answer→Question 151 Mark
State the pH and pOH of 1 M NaOH solution.
AnswerThe pOH of 1 M NaOH is 0 and pH is 14 .
View full question & answer→Question 161 Mark
What will the effect of rise in temperature on value of $K _{ w }$ ?
AnswerOn increasing temperature, ionization of water increases. Hence, $K _{ w }$ increases.
View full question & answer→Question 171 Mark
Find out Lewis acid and base from following :$
H_2 O, BCl_3, FeCl_3, C_2 H_5 OH, PCl_5 .
$
AnswerLewis acid $- BCl _3, FeCl _3, PCl _5$Lewis bases $- H _2 O , C _2 H _5 OH$.
View full question & answer→Question 181 Mark
Which of the following is strongest Lewis acid? $Li ^{+}, K ^{+}, Na ^{+}, Rb ^{+}$
Answer$Li ^{+}$because due to its small size it have high tendency to attract electron.
View full question & answer→Question 191 Mark
Give two examples of aprotic solvents.
AnswerBenzene $\left( C _6 H _6\right)$ and chloroform $\left( CHCl _3\right)$.
View full question & answer→Question 201 Mark
Which will have maximum proton donor capacity? $NH _3, OH ^{-}, SHO _4^{-}$and $H _3 O ^{+}$.
View full question & answer→Question 211 Mark
Which of the following species will be strong proton acceptor? $HPO _4^{-2}, H _2 PO _4^{-}$and $PO _4^{-3}$.
View full question & answer→Question 221 Mark
For two acids HA and HB the value of $K _{ a }$ is $10^{-4}$ and $10^{-6}$ respectively then which conjugate base of these acids will be strong?
Answer HB because $K _{ a }$ of HBr have less value. Hence it is a weak acid. So its conjugate base will be strong.
View full question & answer→Question 231 Mark
Write conjugate bases for $H _2 PO _4^{-}$and HCN .
Answer$HPO _4^{-2}$ and $CN ^{-}$
View full question & answer→Question 241 Mark
Give one example each of real and imaginary electrolytes.
Answer KCl is a real electrolyte while HCl is an imaginary electrolyte.
View full question & answer→Question 251 Mark
In exothermic reaction if temperature is increased what will be the effect on equilibrium constant?
Answer On increasing temperature in exothermic reaction, rate of backward reaction increases. Hence $K _{ c }$ decreases.
View full question & answer→Question 261 Mark
What will be the effect on pH of pure water when temperature increases?
AnswerOn increasing the temperature the ionisation of water increases. Hence $\left[ H ^{+}\right]$will increase and value of pH decreases.
View full question & answer→Question 271 Mark
In solution of electrolyte, by which method electric current is conducted.
Question 281 Mark
What do you meant by ionic equilibrium.
Answer The equilibrium whose aqueous solution have ions, is known as ionic equilibrium.
View full question & answer→Question 291 Mark
$C _2 H _5 OH$ is a Lewis acid or Lewis base. Why?
Answer$C _2 H _5 OH$ is a Lewis base as in $C _2 H _5 OH$, oxygen have 2 lone pair electrons. Hence it is electron pair donor.
View full question & answer→Question 301 Mark
Write a reversible reaction which is not affected by pressure?
Answer$H _2(g)+ I _2(g) \rightleftharpoons 2 HI ( g )$
View full question & answer→Question 311 Mark
In reaction $N _2(g)+3 H _2(g) \rightleftharpoons 2 NH _3(g)$, what will be the effect of increasing pressure?
Answer On increasing pressure in above reaction more $NH _3(g)$ will form.
View full question & answer→Question 321 Mark
In formation of ammonia if $100 ml $ N2 react, then how many ml of $H _2$ react?
Answer According to $N _2(g)+3 H _2(g) \rightleftharpoons 2 NH _3(g)$ $100 ml N _2$ react with 300 ml of $H _2$.
View full question & answer→Question 331 Mark
If for reaction $N _2(g)+3 H _2(g) \rightleftharpoons 2 NH _3(g)$ the equilibrium constant $K _{ c }=9$ then for reaction $NH _3(g)$ $\rightleftharpoons \frac{1}{2} N_2(g)+\frac{3}{2} H _2(g)$, what will be the value of equilibrium constant $K _{ c }^{\prime}$ ?
Answer $K _{ c }^{\prime}=\frac{1}{\sqrt{K_{ c }}}=\frac{1}{\sqrt{9}}=\frac{1}{3}$
View full question & answer→Question 341 Mark
Write $K_c$ and $K_p$ for following heterogeneous equilibrium :
$
CaCO_3(s) \rightleftharpoons CaO(s)+CO_2(g)
$
Answer$
\begin{array}{l}
K_{o}=\left[CO_2(g)\right] \\
K_{p}=P_{CO_2}
\end{array}
$
View full question & answer→Question 351 Mark
What is standard melting point?
AnswerAt atmospheric pressure, the temperature of a pure substance (solid) at which solid and liquid states are in equilibrium are called standard melting or freezing point.
View full question & answer→Question 361 Mark
Give the expression of equilibrium constant $K _{ c }$ for reaction $NH _4 Cl ( s ) \rightleftharpoons NH _3(g)+ HCl ( g )$.
Answer$K _{ c }=\left[ NH _3\right][ HCl ]$
View full question & answer→Question 371 Mark
Which out of following are not Lewis acids :
$
BF_3, NH_3, H_2 O, AlCl_3 ?
$
Answer$NH _3$ and $H _2 O$.
View full question & answer→Question 381 Mark
For reaction $2 X ( g ) \rightleftharpoons Y ( g )+ Z ( g )$, at equilibrium $[ X ]=2 M ,[ Z ]=8 M$ and $K _{ c }=1$ then what will be $[ Y ]$ ?
Answer$
\begin{aligned}
K_{c} & =\frac{[Y][Z]}{[X]^2} \\
1 & =\frac{[Y][8]}{[2]^2}
\end{aligned}
$
$
\text { Hence } \quad[Y]=\frac{4}{8}=0.5
$
View full question & answer→Question 391 Mark
If concentration of $A$ and $B$ are doubled in reaction $A +2 B \rightleftharpoons 2 C$ then how much velocity of forward reaction increases?
AnswerVelocity $= K [ A ][ B ]^2$
When concentration of A and B are doubled,
$
\begin{aligned}
\text { Velocity } & =K[2 A][2 B]^2 \text { or } \\
V & =8 K[A][B]
\end{aligned}
$
Hence its velocity becomes 8 times.
View full question & answer→Question 401 Mark
Write relationship between $K_p$ and $K_c$ for following reactions :
$
N_2(g)+3 H_2(g) \rightleftharpoons 2 NH_3(g)
$
Answer$\begin{array}{l}\text { For } N _2(g)+3 H _2(g) \rightleftharpoons 2 NH _3(g) \\ \\ \text { Hence } \\ \\ \Delta n =-2 \\ \\ K_{ p }= K _{ c }( RT )^{\Delta n } \\ \\ K _{ p }= K _{ c }( RT )^{-2}\end{array}$
View full question & answer→