Which of the given statements for mercury cell are incorrect?
(i) Mercury cell is suitable for low current devices like hearing aids, watches, etc.
(ii) It consists of zinc-mercury amalgam as anode and a paste of HgO and carbon as the cathode.
(iii) The electrolyte is a paste of $Z n (O H)_{2}$ and $K O_{2}$ .
(iv) The electrode reactions for the cell are
At anode: $Z n (H g) + H_{2} O \to Z n O_{(s)} + 2 O H^{-} + 2 e^{-}$
At cathode: $H g O + H_{2} O + 2 e^{-} \to H g_{(l)} + 2 O H^{-}$

(ii) and (iii) only

No worries! We‘ve got your back. Try BYJU‘S free classes today!

(i) ad (ii) only

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

(i), (iii) and (iv) only

No worries! We‘ve got your back. Try BYJU‘S free classes today!

(iii) and (iv) only

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is C (i) ad (ii) only
Mercury cell is alkaline dry cell.
$Z n | Z n (O H)_{2} (s) K O H (a q) H g O (s) | H g$
Cell voltage $= 1.34$ $V$
Hence, used for low current devices.

$Z n | Z n O ⟶$ Anode- Amalgamated zinc
$H g O (s) C (s) ⟶$ Cathode- Mercuric oxide/Graphite
$K O H ⟶$ Electrolyte

Reaction at anode- $Z n (H g) + 2 O H^{⊝} ⟶ Z n O (s) + H_{2} O + 2 e^{-}$

Cathode- $H g O + H_{2} O + 2 e^{-} ⟶ H g (l) + O H^{⊝}$

Option B is correct.

Suggest Corrections

Similar questions

Q. Assertion :In mercury cell, the cell potential is approximately

1.35

V and remains constant during its life. Reason: The overall reaction in mercury cell is represented as

Z n (H g) + H g O_{(s)} \to Z n O_{(s)} + H g_{(l)}

Question 23
An electrolytic cell consists of:
(i) positively charged cathode.
(ii) negatively charged anode.
(iii) positively charged anode.
(iv) negatively charged cathode.

(a) (i) and (ii)
(b) (iii) and (iv)
(c) (i) and (iii)
(d) (ii) ad (iv)

Q. Assertion :The cell potential of mercury cell is

1.35 V

, which remains constant. Reason: In mercury cell, the electrolyte is a paste of

K O H

and

Z n O

Q. In which of the following reactions

H_{2} O_{2}

acts as reducing agent?
I.

H_{2} O_{2} + 2 H^{+} + 2 e^{-} \to 2 H_{2} O

II.

H_{2} O_{2} - 2 e^{-} \to O_{2} + 2 H^{+}

III.

H_{2} O_{2} + 2 e^{-} \to 2 O H^{-}

IV.

H_{2} O_{2} + 2 O H^{-} - 2 e^{-} \to O_{2} + 2 H_{2} O

Q. An electrolytic cell consists of
(i) positively charged cathode
(ii) negatively charged anode
(iii) positively charged anode
(iv) negatively charged cathode

Join BYJU'S Learning Program