Model Test Questions XI Chemistry on Electrochemistry and Oxidation Number (Chapter # 12)

Short Questions

Q1. Define the terms oxidation, reduction, oxidizing agent, reducing agent and redox reactions in terms of electron transfer. Identify the oxidizing agent and reducing agent in following equation:

Mg + H₂SO₄ → MgSO₄ + H₂

Q2*. Distinguish between the following

(i) Primary and secondary cell,

(ii) Oxidation and reduction

(iii) Oxidizing and reducing agent.

(iv) Oxidation number and valency

Q3*. What is meant by oxidation number? State its rules

Q4*. Determine the oxidation number of central atom in following

(i) Cr in H₂CrO₄

(ii) S in K₂S₄O₆

(iii) Fe in Fe₃O₄

(iv) Cl in HClO₄

Q5. Examine the following chemical equations and Identify the redox reactions out of the following reactions and indicate the oxidation, reduction, oxidizing and reducing agent in them.

(i) HNO₃ +2HCl → NOCl + Cl₂ + 2H₂O

(ii) HgCl₂ + 2KI → HgI₂ + 2KCl

(iii) Fe₂O₃ + 3CO → 2Fe + 3CO₂

(iv) PCl₃ + 3H₂O → 3HCl + H₃PO₃

(v) H₂S + Br₂ → 2HBr + S

(vii) 4NH₃ + 3O₂ → 2N₂ + 6H₂O

(viii) H₂+ Cl₂ → 2HCl

(vii) Zn + Cl₂ → ZnCl₂

(ix) 2Ca + O₂ → CaO

(x) 2Li + S → Li₂S

Q6. Identify the oxidizing and reducing agents from the following.

(i) Al (RA)

(ii) Na (RA)

(iii) H₂S (RA)

(iv) H₂SO₄ (OA)

(v) KMnO₄ (OA)

(vi) Zn (RA)

Q7. What is the oxidation number of sulphur in following compounds?

H₂SO₃, S₂O₃^2‒, S₂Cl₂, SF₆, SO₂Cl₂

Q8. What is the oxidation number of chromium in following compounds?

CrO₃, CrO₂, Cr₂O₇²¯, CrO₂¹¯, CrO₂Cl₂

Q9. Determine the oxidation number of central atom in following

(i) S in Na₂S₂O₃

(ii) Mn in MnO₄⁻

(iii) Cr in Cr₂O₇²⁻

(iv) Cl in ClO₃

(v) Cr in Cr₂(SO₄)₃

(vi) P in Ca(H₂PO₄)₂

(vii) S in H₂SO₄

(viii) Ni in Ni(CO)₄

(ix) Fe in Fe₃O₄

(x) C in C₃O₄

(xi) Fe(CO)₃

(xii) Cr(CO)₆

Q10. Calculate the oxidation number of central element in following:

Q11. Calculate the oxidation number of central element in following:

(i) C in C₂H₆O

(ii) C in C₄H₈O₂

(iii) C in CH₃Cl

(iv) Cr in CrO₂Cl₂

(v) C in COCl₂

(vi) N in NOCl

(vii) UO₂Cl₂

(viii) BiOCl

(ix) S in SO₂Cl

(x) S in SOCl₂

(xi) S in HSO₃F

(xii) C in HCNS

Q12. Calculate the oxidation number of central element in following:

(i) P in POCl₃

(ii) CNO⁻

(iii) Cl in CaOCl₂ (Bleaching powder)

(iv) S in Na₂S₄O₆

(v) N in NH₄NO₃

(vi) Br in BrO₃⁻

Q13. Calculate the oxidation number of central element in following:

(1) Cr in K₂Cr₂O₇ and CrO₂−

(2) Cl in Mg(ClO₄)₂ and ClO₂−

(3) P in Na₄P₂O₇ and H₃PO₄

(4) N in NH₄Cl and HNO₂

(5) N in NH₃ and NCl₃

(6) Mn in KMnO₄ and MnO₄−

(7) O in OF₂and H₂O₂

(8) O in KO₂and O₂F₂

(9) O in BaO₂and Na₂O₂

(10) S in Na₂S₄O₆ and S₂O₃²−

(11) S in H₂S₂O₇ and SO₂Cl₂

(12) Cr in CrO₂Cl₂ and CrO₄²−

(13) H in CaH₂ and NaH

(14) Mn in Mn₂O₇ and MnO₂

(15) C in C₆H₁₂O₆ and C₁₂H₂₂O₁₁

(16) C in C₂H₄O₂ and CH₂O

(17) Mn in Mn₂O₃ and MnO₄²⁻

Q14. Define the term standard electrode potential and hydrogen electrode.

Q15. In the process of electroplating the item to be plated is made cathode, give reason?

Q16. What is corrosion? What causes it to form? What can be done to prevent its formation?

Q17. How can you define an electrochemical series? Give its properties.

Q18. What is Electrolysis and electrochemistry? Name two parts of Redox reactions that occurs in electrolysis of molten CaCl₂or sodium chloride and state where each occurs and describe its electrolysis.

Descriptive Questions

Q1. What is meant be electrode potential and hydrogen electrode (SHE). Describe how the electrode potential of zinc or copper is determined?

Q2. What is Galvanic cell? Sketch a copper-zinc Galvanic ell, write the cell reaction, cell diagram and shows the direction of electron flow.

Q3. What is the difference between a primary cell and secondary cell. Sketch a diagram of dry cell and explain its working.

Q4. Balance the any 2 of the following equations by ion electron method attempting one in acidic medium and one in basic medium

H₂S + HNO₃ → S + NO + H₂O (acidic medium)

CuS + NO₃^‒ → CuSO₄ + NO (acidic medium)

MnO₄^‒ + C₂O₄^2‒ → Mn²⁺ + CO₂ (acidic medium)