Balancing Redox Equations

Q. For the redox reaction,
$Mn{O}_4^{-}+C_2{O}_4^{2-}+H^{+}\to M{n}^{2+}+C{O}_2+H_{2}O$, the correct coefficients of the reactants, i.e. $Mn{O}_4^{-},C_2{O}_4^{2-},H^{+}$ for the balanced reaction are respectively :

1. $2,5,16$
2. $16,3,12$
3. $15,16,12$
4. $2,16,5$

Q.

n-factor of ${\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7$ is

Q. The number of electrons required to balance the following equation are
$N{O}_3^{-}+4H^{+}+e^{-}⟶2H_{2}O+NO$

1. $4$
2. $3$
3. $5$
4. $2$

Q.

What is the equivalent mass of HCl in the given reaction?

$2KMn{O}_4+16HCl\to 2KCl+2MnC{l}_2+5C{l}_2+8H_{2}O$

1. 44.2
2. 36.5
3. 58.4
4. none of these

Q. If $0.5$ mole of $BaC{l}_2$ is mixed with $0.2$ mole of $N{a}_{3}P{O}_4$, the maximum number of moles of $B{a}_3(P{O}_4{)}_2$ that can be formed is

1. $0.70$
2. $0.50$
3. $0.20$
4. $0.10$

Q. Complete combustion of 3 g ethane gives $x\times {10}^{22}$ molecules of water. The value of x is
(Round off to the nearest integer)
[Use : $N_A=6\times {10}^{23}$

Q. $2,4$-DNP test can be used to identity:

1. Halogens
2. Aldehyde
3. Ether
4. Amine

Q. The ionization constant of $HF$ is $3.2\times {10}^{-4}$. Calculate the degree of dissociation of $HF$ in its $0.02M$ solution. Calculate the concentration of all species present $(H_3{O}^{+},F^{-}\text{and}HF)$ in the solution and its pH.

Q.

In a basic medium, H₂O₂ exhibits which of the following reactions?

A. Mn²⁺ → Mn⁴⁺

B. I₂ → I^–

C. PbS → PbSO₄

1. (A), (C) only

2. (A) only

3. (B) only

4. (A), (B) only

Q. How many mL of $0.1NHCl$ are required to react completely with $1g$ mixture of $N{a}_{2}C{O}_3$ and $NaHC{O}_3$ containing equimolar amounts of both?

1. $200.7$
2. $300.0$
3. $257.8$
4. $157.8$

Q. The molecular formula of a commercial resin used for exchanging ions in water softening is $C_8{H}_{7}S{O}_{3}Na(Mol.Wt.206gmo{l}^{-1})$ .What would be the maximum uptake of $C{a}^{2+}$ ions by the resin when expressed in mole per gram resin?

1. $\frac{1}{206}$

2. $\frac{2}{309}$
3. $\frac{1}{412}$
4. $\frac{1}{103}$

Q. What is the percent yield of the following reaction if $50\text{g}$ of $CaC{O}_3$ is heated to give $15\text{g}$ of CaO?
$CaC{O}_3\to CaO+C{O}_2$

1. $44.6\%$
2. $50.0\%$
3. $66.6\%$
4. $53.5\%$

Q. To a $10\text{mL}$ of ${10}^{-3}N{H}_{2}S{O}_4$ solution water has been added to make the total volume of one litre. Its $pOH$ would be:

1. $3$
2. $5$
3. $9$
4. $9.3$

Q.

$0.02\mathrm{M}$ ${\mathrm{K}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7$ when reacts with $0.0288\mathrm{g}$ Ferrous Oxalate in an acidic medium. What is its volume(in ml)? $(\mathrm{Molar}\mathrm{mass}\mathrm{of}\mathrm{Fe}=56\mathrm{g}{\mathrm{mol}}^{-1})$

Q. The reactant which is entirely consumed in reaction is known as limiting reagent.In the reaction $2A+4B\to 3C+4D$, when 5 moles of A react with 6 moles of B, then


A) Which is the limiting reagent

B)Calulate the amount of C Formed.

Q. In dilute aqueous $H_{2}S{O}_4$, the complex diaquodioxalatoferrate (II) is oxidized by $Mn{O}_4^{-}$. For this reaction, the ratio of the rate of change of $\left[H^{+}\right]$ to the rate of change of $\left[Mn{O}_4^{-}\right]$ is

Q.

For the redox reaction
$Mn{O}_4^{-}+C_2{O}_4^{-2}+H^{+}⟶M{n}^{2+}+C{O}_2+H_{2}O$
the correct coefficients of the reactants $Mn{O}_4^{-},C_2{O}_4^{2-}and{H}^{+}$ for the balanced reaction are

1. 2, 5, 16

2. 16, 5, 2

3. 5, 16, 2

4. 2, 16, 5

Q.

The number of electrons involved in the reduction of $C{r}_2{O}_7^{2-}$ in acidic solution to $C{r}^{3+}$ is

1. 0

2. 2

3. 3

4. 5

Q. Hydrazine $\left(N_2{H}_4\right)$ can be produced according to the following reaction:
$ClN{H}_2+2N{H}_3\to N_2{H}_4+N{H}_{4}Cl$. 1 kg of $ClN{H}_2$ is reacted with excess $N{H}_3$, find the actual number of molecules of $N_2{H}_4$ produced if the percentage yield of the given reaction is 76%.

1. $15N_A$
2. $13N_A$
3. $17N_A$
4. $3.2N_A$

Q. A mixture of 0.02 mole of $KBr{O}_3$ and 0.01 mole of $KBr$ was treated with excess of $KI$ and acidified. The volume of 0.1 $MN{a}_2{S}_2{O}_3$ solution required to consume the liberated iodine will be:

1. 1200 mL
2. 800 mL
3. 1000 mL
4. 1500 mL

Q. Which is stronger reducing agent $F{e}^{2+}$ (or) $C{r}^{2+}$. Why?

Q. For the preparation of $H_{2}S{O}_4$ from iron pyrite $\left[Fe{S}_2\right]$ involves following set of reaction.
$Fe{S}_2+O_2\to F{e}_2{O}_3+S{O}_2$
$S{O}_2+O_2\to S{O}_3$
$S{O}_3+H_{2}O\to H_{2}S{O}_4$
Calculate the weight of $H_{2}S{O}_4$ which can be obtained when $240\text{kg}$ of $Fe{S}_2$ is used.

1. $392\text{kg}$
2. $412\text{kg}$
3. $329\text{kg}$
4. $292\text{kg}$

Q. x mmol of $KMn{O}_4$ reacts completely with y mmol of $MnS{O}_4$ in the presence of fluoride ions to give $Mn{F}_4$ quantitatively, then:

1. 4x = 1
2. x > y
3. x < y
4. x = 4

Q. Write the balanced equation for the following chemical reactions:

1. $2Na\left(s\right)+2H_{2}O\left(l\right)\to 2NaOH\left(aq\right)+H_2\left(g\right)$
2. $Na\left(s\right)+H_{2}O\left(l\right)\to NaOH\left(aq\right)+H_2\left(g\right)$
3. $2Na\left(s\right)+2H_{2}O\left(l\right)\to NaOH\left(aq\right)+H_2\left(g\right)$
4. $Na\left(s\right)+H_{2}O\left(l\right)\to 2NaOH\left(aq\right)+H_2\left(g\right)$

Q. Consider the following reaction:
$xMn{O}_4^{-}+y{C}_2{O}_4^{2-}+z{H}^{+}\to xM{n}^{2+}+2yC{O}_2+\frac{z}{2}{H}_{2}O$
The values of x, y and z in the reaction are, respectively:

1. 5, 2 and 16
2. 2, 5 and 16
3. 2, 5 and 8
4. 5, 2 and 8

Q.

How many moles of $K_{2}C{r}_2{O}_7$ can be reduced by 1 mole of $S{n}^{+2}$

1. $\frac{1}{3}$

2. $\frac{1}{6}$

3. $\frac{2}{3}$

4. 1

Q. The enthalpy of neutralization of four acids $HA$, $HB$, $HC$ and $HD$ with $NaOH$ are $-13,-12,-11$ and $-10$ Kcal/mol. Which salt has maximum degree of hydrolysis?

1. $\text{1 M NaA}$
2. $\text{1 M NaD}$
3. $\text{1 M NaB}$
4. $\text{1 M NaC}$

Q. For 0.50 M aqueous solution of sodium cyanide, $\left({\text{pK}}_{\text{b}}{\text{of CN}}^{-}\text{is}4.70\right)$, calculate hydrolysis constant.

1. $1.03\times {10}^{-15}$
2. $1.03\times {10}^{-12}$
3. $1.99\times {10}^{-5}$
4. None of the above

Q. $2.48\text{g of}N{a}_2{S}_2{O}_3$. $x{H}_{2}O$ is dissolved per litre of solution. $20\text{mL}$ of this solution required $10\text{mL}$ of $0.01\text{M}$ iodine solution for a complete reaction. What is the value of $x$?

Q. A 3.4 $g$ sample of $H_2{O}_2$ solution containing x% by mass requires $x$ ml of a $KMn{O}_4$ solution for complete oxidation under acidic medium. The molarity of $KMn{O}_4$ solution is:

1. 1.0 M
2. 0.5 M
3. 0.4 M
4. 0.2 M