Chemistry Questions & Answers - Free Online Practice

2,916.

Cr₂O₇^2-_(aq) + 14H⁺_(aq) + 6l^-_(aq) → 2Cr³⁺_(aq) + 3l_(g) + 7H₂O_(I).
The change in the oxidation number of oxygen in the equation above is?

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Correct answer is A

No explanation has been provided for this answer.

2,917.

Which of the following is a redox reaction?

KCI_(aq) + H₂SO_4(aq) → KHSO_4(aq) + HCI_(aq)

2FeBr_2(aq) + Br_4(aq) → 2FeBr_3(aq)

3AgNO_(aq) + FeCl_3(aq) → 3AgCl_(aq) + Fe(NO₃)_3(aq)

H₂CO_3(aq) → H₂O_(I)2- + CO_2(g)

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Correct answer is B

No explanation has been provided for this answer.

2,918.

2CL^-_(aq) → CI_2(g) + 2e^-(aq). The above half-cell reaction occuring at the anode during the electrolysis of dilute ZnCI₂ solution is?

ionization

oxidation

reduction

recombination

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Correct answer is B

No explanation has been provided for this answer.

2,919.

How many moles of copper would be deposited by passing 3F of electricity through a solution of copper (II) tetraoxosulpohate (IV)?

(F = 96 500 C mol^-)

0.5

1.0

1.5

3.0

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Correct answer is C

No explanation has been provided for this answer.

2,920.

In the process of silver-plating a metal M, the metal M is the?

anode and a direct current is used

cathode and an alternating current is used

anode and an alternating current is used

cathode and a direct current is used

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Correct answer is D

Plating requires ions to flow through an electrolyte in an electric field. Positive ions flow with the electric field, negative ions against the electric field. This electric field comes from a DC supply connected to the electrodes. While silver plating, Ag is the anode while the metal to be coated is the cathode.