Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.

Electrochemistry

Short Answer Type

181. Write the Nernst equation and emf of the following cells at 298 k.
Mg(s) | Mg²⁺ (0.001 M) || Cu²⁺ (0.0001 M) | Cu(s)

174 Views

182. Write the Nernst equation and emf of the following cells at 298 k.
Fe(s) | Fe²⁺ (0.001 M) || H⁺ (1M) | H₂ (g) (1 bar) | Pt(s)

174 Views

183. Write the Nernst equation and emf of the following cells at 298 k.
Sn(s) | Sn²⁺ (0.050 M) || H⁺(0.020 M) H₂(g) (1bar) Pt (s)

324 Views

184. Write the Nernst equation and emf of the following cells at 298 k.
Pt(s) | Br₂ (l) | Br^– (0.010 M) || H⁺ (0.030 M) | + H₂(g) (1 bar) | Pt(s).

208 Views

185. What is corrosion? What are the factors which affect corrosion?

150 Views

186. CO₂ is always present in natural water. Explain its effect (increases, stops or no effect) on rusting of iron.

CO₂ increases rusting of iron: CO₂ present in water is in the form of H₂CO_3. H₂CO₃dissociates into H⁺ and HCO₃-.

H_{2} {CO}_{3} = {HCO}_{3}^{-} + H^{+} H_{2} O = H^{+} + {OH}^{-} 2 H^{+} + 2 e \to H_{2}

Hydroxyl ion or bicarbonate ions attack the iron surface to form anodic regions in which iron loses electrons and pass on to ferrous sulphate which is further oxidised to ferric state by oxygen of the air. The released electrons move towards the cathode region where H⁺ions are converted into hydrogen gas.

Fe \to {Fe}^{2 +} + 2 e^{-} O_{2} = 2 H_{2} O + 4 e^{-} \to 4 {OH}^{-} 4 Fe + 3 O_{2} + 2 \times H_{2} O \to 2 {Fe}_{2} O_{3} . {XH}_{2} O

Thus CO₂ increases rusting because H₂CO₃gives H⁺ which gain electrons to form H₂ gas. The electrons are released by iron.

545 Views

187. Rusting of iron is quicker in saline water than in ordinary water. Explain.

697 Views

188. We can use aluminium in place of zinc for cathodic protection of rusting. Comment.

1149 Views

189. How is cathodic protection of Iron different from its galvanisation?

185 Views

Long Answer Type

190. Define conductivity and molar conductivity for the solution of an electrolyte. Discuss their variaion with concentration.

419 Views