Redox Reactions Test

Result

Redox Reactions Test - 73

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Weekly Quiz Competition

Question 1
1 / -0

In which of the following compounds, Fe has the lowest oxidation number?

A
$$ \mathrm{K}_{3}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right] $$

B
$$ \mathrm{Fe}(\mathrm{CO})_{5} $$

C
$$ \mathrm{FeCl}_{2} $$

D
$$ \mathrm{FeSO}_{4}\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4} \cdot 6 \mathrm{H}_2 \mathrm{O} $$

Solution
Question 2
1 / -0

The value of $$n$$ in the reaction is:

$$Cr_{2}O_{7}^{2-}+14H^{+}+nFe^{2+}\rightarrow 2Cr^{3+}+nFe^{3+}+7H_{2}O$$

A
$$2$$

B
$$3$$

C
$$6$$

D
$$7$$

Solution
Question 3
1 / -0

Oxidation number of oxygen in ozone $$\left( \mathrm { O } _ { 3 } \right)$$ is:

A
$$+ 3$$

B
$$- 3$$

C
$$- 2$$

D
0
Question 4
1 / -0

Oxidation number of oxygen in $$NaO_{ 3 }, { KO }_{ 2 }$$ respectively are:

A
3, 2

B
1, 0

C
0, 1

D
-0.33, -0.5

Solution
Question 5
1 / -0

Which of the following statement is correct?

A
$$ MnO^-_4 $$ is very good oxidant in acidic medium and liberates iodine when added to $$KI$$ solution by forming $$ MnO_2 $$.

B
$$ MnO^-_4 $$ is a very good oxidant in basic medium and liberates iodine when added to $$KI$$ solution by forming $$ MnO_2 $$.

C
$$ MnO^-_4 $$ is very good oxidant in acidic medium and liberates iodine when added to $$KI$$ solution by forming $$ Mn^{2+} $$.

D
$$ MnO^-_4 $$ is very good oxidant in basic medium and liberates iodine when added to $$KI$$ solution by forming $$ Mn^{2+} $$.
Question 6
1 / -0

What is the molar concentration of the triiodide solution, $$KI_3$$(aq), if 30.00 mL of the solution is required to completely react with 25.00 mL of a $$0.200\ mol/L$$, thiosulphate solution, $$K_2S_2O_3$$(aq) ?
The chemical equation for the reaction is:
$$2S_2O_3^{2-}(aq) + I_3^-(aq)\rightarrow S_4O_6^{2-} (aq)+3 I^-(aq)$$

A
0.0333 M

B
0.12 M

C
0.0833 M

D
0.00012 M
Question 7
1 / -0

Oxidation number of nitrogen in $$ (NH_4)_2SO_4 $$ is

A
$$ - \cfrac {1}{3} $$

B
$$ -1 $$

C
$$ +1 $$

D
$$ -3 $$

Solution
Question 8
1 / -0

Which of the following is a redox reaction?

A
$$NaCl+K{NO}_{3}\rightarrow Na{NO}_{3}+KCl$$

B
$$Ca{C}_{2}{O}_{4}+2HCl\rightarrow Ca{Cl}_{2}+{H}_{2}{C}_{2}{O}_{4}$$

C
$$Mg{(OH)}_{2}+2{NH}_{4}Cl\rightarrow Mg{Cl}_{2}+2{NH}_{4}OH$$

D
$$Zn+2AgCN\rightarrow 2Ag+Zn{(CN)}_{2}$$

Solution

Option D is correct.
Question 9
1 / -0

The atomic number of an element is 22. The highest oxidation state exhibited by it in its compounds is

A
1

B
2

C
3

D
4

Solution

Electronic configuration for $$Z=22$$ is $$[Ar]3d^24s^2.$$

Highest oxidation state $$=$$ no. of $$ns$$ electron $$+$$ no. of $$(n-1)d$$ electrons.

$$=\,\,\,2+\,\,\,2=4$$
Question 10
1 / -0

Acidified potassium dichromate is treated with hydrogen sulphide. In the reaction, the oxidation number of chromium

A
increases from +3 to +6

B
decreases from +6 to +3

C
remains uncharged

D
decreases from +6 to +2

Solution

The oxidation number of chromium decreases from +6 to +3.

$$ K_2Cr_2O_7 +4H_2SO_4 \rightarrow K_2SO_4 + Cr_2(SO_4)_3 + 4H_2O + 3O$$

$$ [ H_2S +[O] \rightarrow S+ H_2O] \times 3 $$
_______________________________
$$ K_2\overset{+6} {Cr_2}O_7 + 4H_2SO_4 +3H_2S \rightarrow K_2SO_4 +\overset{+3}{Cr_2}(SO_4)_3 + 7H_2O +3S $$