Electrochemistry Test

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Electrochemistry Test - 36

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Question 1
1 / -0

On electrolysis, water splits into

A
positively charged hydrogen ions and negatively charged oxygen ions.

B
negatively charged hydrogen ions and positively charged oxygen ions.

C
hydrogen and oxygen atoms having positive and negative charges respectively.

D
hydrogen and oxygen atoms having negative and positive charges respectively.

Solution

The electrolysis of water $$(H_2O)$$ produces the positive ion of hydrogen atom $$(H^+)$$ and negative ion of oxygen $$(O^-)$$.
Question 2
1 / -0

Electrolysis of a dilute solution of aqueous sodium chloride results in the cathode product:

A
Sodium

B
Hydrogen

C
Chlorine

D
Oxygen

E
Peroxide

Solution

In electrolysis of aqueous sodium chloride, both $$H^+$$ and $$Na^+$$ will compete with each other for reduction and as the reduction potential of $$H^+$$ is more compared to $$Na^+$$, so $$H^+$$ will get reduced first at cathode and hydrogen gas will be liberated at cathode.
Question 3
1 / -0

......................................acts as the anode.

A
$$Zn(s)$$

B
$$Cu^{2+}(aq)$$

C
$$Zn^{2+}(aq)$$

D
$$Cu(s)$$

E
$$H_2O$$

Solution

$$Zn^{2+}+2e^-\rightarrow Zn, \ E^0=-0.76V$$
As the reduction potential of $$Zn$$ is negative, oxidation of $$Zn$$ will take place and the $$Zn(s)$$ will act as anode..
Question 4
1 / -0

For $$Cu(s) + NO_3^- (aq) + H^+(aq) \rightarrow Cu^{2+}(aq) + NO_2(g) + H_2O(l)$$, which of the following takes place?

A
$$Cu(s)$$ is oxidized

B
$$H^+ (aq)$$ is oxidized

C
$$Cu(s)$$ is reduced

D
$$H^+ (aq)$$ is reduced

E
$$NO_3^-$$ is oxidized.

Solution

Oxidation state of $$Cu$$ changes from $$0$$ to $$+2$$
Oxidation state of $$N$$ changes from $$+5$$ to $$+4$$
Oxidation state of $$H^+$$ remains same

therefore, $$Cu$$ is getting oxidised and $$NO_3^-$$ is getting reduced.
Question 5
1 / -0

______________ acts as the cathode.

A
$$Zn(s)$$

B
$$Cu^{2+}(aq)$$

C
$$Zn^{2+}(aq)$$

D
$$Cu(s)$$

E
$$H_2O$$

Solution

$$Cu^{2+}+2e^-\rightarrow Cu, \ E^0=+0.34V$$
As the reduction potential of $$Cu^{2+}$$ is positive, Reduction of $$Cu$$ will take place and the $$Cu(s)$$ will act as cathode.
Question 6
1 / -0

Whats the potential of the reaction below given the half-reaction potentials:
$$2Fe_2+ + Cl_2 \rightarrow 2Fe^{3+} + 2Cl^-$$
$$Fe^{3+} + e^- \rightarrow Fe^{2+}; E = 0.77 V$$
$$Cl_2 + 2e^- \rightarrow 2Cl^- ; E = 1.36 V$$

A
$$0.18 V$$

B
$$0.59 V$$

C
$$1.05 V$$

D
$$2.13 V$$

E
$$2.90 V$$

Solution

$$2Fe^{2+}+Cl_2\rightarrow 2Fe^{3+}+2Cl^-$$
$$E^0_{reaction}=E^0_{cathode}-E^0_{anode}$$
$$=1.36-0.77$$
$$=0.59V$$
Question 7
1 / -0

In a double bond connecting two atoms there is sharing of:

A
2 electrons

B
4 electrons

C
1 electron

D
none

Solution

In a double bond connecting two atoms, there is sharing of four electrons between double-bonded atoms, one sigma one pi.
Question 8
1 / -0

$$Cu^{2+}(aq)+Zn(s)\rightarrow Zn^{2+}(aq)+Cu(s)$$
In the above reaction which of the following is reduced?

A
$$Zn(s)$$

B
$$Cu^{2+}(aq)$$

C
$$Zn^{2+}(aq)$$

D
$$Cu(s)$$

E
$$H_2O$$

Solution

$$Cu^{2+}(aq)+Zn(s)\rightarrow Zn^{2+}(aq)+Cu(s), \ E^0=0.34-(-0.76)=1.10V$$

In the above reaction $$Cu^{2+}(aq)$$ is getting reduced and $$Zn$$ is getting oxidised to $$Zn^{2+}$$.
Question 9
1 / -0

For the following reactions:
$$Zn \rightarrow Zn^{2+} + 2e^-; E=+0.76 V$$
$$Au \rightarrow Au^{3+} + 3e^-; E=-1.42 V$$
If gold foil is placed in a solution containing $$Zn^{2+}$$, the reaction potential would be:

A
$$-1.34 V$$

B
$$-2.18 V$$

C
$$-0.66 V$$

D
$$+2.18 V$$

E
$$+1.34 V$$

Solution

If gold foil is placed in a solution containing $$Zn^{2+}$$, Gold will be reduced and Zinc will be oxidised and the following reaction will take place:
$$3Zn+2Au^{3+}\rightarrow 3Zn^{2+}+2Au$$
The reaction potential for the above reaction is given by :
$$E=E_{cathode}-E_{anode}=-1.42-0.76=-2.18 \ V$$
Question 10
1 / -0

Which of these statements best describes a galvanic cell?

A
Reduction occurs at the anode.

B
Oxidation occurs at the anode.

C
Energy is required from an external source.

D
The thode is negative.

E
$$E^o_{cell}$$ is negative.

Solution

In any galvanic cell, oxidation occurs at anode and reduction occurs at cathode.

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Electrochemistry Test - 36

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Electrochemistry Test - 36

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Question 1

positively charged hydrogen ions and negatively charged oxygen ions.

negatively charged hydrogen ions and positively charged oxygen ions.

hydrogen and oxygen atoms having positive and negative charges respectively.

hydrogen and oxygen atoms having negative and positive charges respectively.

Solution

Question 2

Sodium

Hydrogen

Chlorine

Oxygen

Peroxide

Solution

Question 3

$$Zn(s)$$

$$Cu^{2+}(aq)$$

$$Zn^{2+}(aq)$$

$$Cu(s)$$

$$H_2O$$

Solution

Question 4

$$Cu(s)$$ is oxidized

$$H^+ (aq)$$ is oxidized

$$Cu(s)$$ is reduced

$$H^+ (aq)$$ is reduced

$$NO_3^-$$ is oxidized.

Solution

Question 5

$$Zn(s)$$

$$Cu^{2+}(aq)$$

$$Zn^{2+}(aq)$$

$$Cu(s)$$

$$H_2O$$

Solution

Question 6

$$0.18 V$$

$$0.59 V$$

$$1.05 V$$

$$2.13 V$$

$$2.90 V$$

Solution

Question 7

2 electrons

4 electrons

1 electron

none

Solution

Question 8

$$Zn(s)$$

$$Cu^{2+}(aq)$$

$$Zn^{2+}(aq)$$

$$Cu(s)$$

$$H_2O$$

Solution

Question 9

$$-1.34 V$$

$$-2.18 V$$

$$-0.66 V$$

$$+2.18 V$$

$$+1.34 V$$

Solution

Question 10

Reduction occurs at the anode.

Oxidation occurs at the anode.

Energy is required from an external source.

The thode is negative.

$$E^o_{cell}$$ is negative.

Solution

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