ECAT — Engineering College Admission Test (UET)
Take the ECAT Chemistry — Solutions and Electrochemistry (Set 2): 30 multiple-choice questions (40 minutes) with instant scoring and a full answer review.…
What this test covers
The first 5 questions of this test, with the correct answer and explanation.
Q1. 4.9 g of H₂SO₄ (M = 98) is dissolved in water to make 500 cm³ of solution. Its molarity is:
Answer: B. 0.1 M
Explanation: Moles = 4.9/98 = 0.05 mol; M = 0.05/0.5 dm³ = 0.1 M.
Q2. What mass of NaCl (M = 58.5) is needed to prepare 250 cm³ of a 0.2 M solution?
Answer: C. 2.925 g
Explanation: Moles = 0.2 × 0.25 = 0.05 mol; mass = 0.05 × 58.5 = 2.925 g.
Q3. 6 g of urea (M = 60) is dissolved in 250 g of water. The molality of the solution is:
Answer: C. 0.4 m
Explanation: Moles = 6/60 = 0.1 mol; molality = 0.1/0.250 kg = 0.4 mol kg⁻¹.
Q4. The mole fraction of the solute in a 1 molal aqueous solution is about:
Answer: B. 0.018
Explanation: 1 mol solute per 1000 g water (55.5 mol): x = 1/(1 + 55.5) ≈ 0.0177.
Q5. Concentrated HCl is 36.5% HCl by mass and has a density of 1.2 g cm⁻³. Its molarity is:
Answer: B. 12 M
Explanation: 1 dm³ has mass 1200 g, of which 0.365 × 1200 = 438 g is HCl = 12 mol; so 12 M.
Take the timed test (free, no sign-up) to see your score and the answer and explanation for every question.
Q6. 100 cm³ of 0.5 M NaCl is mixed with 300 cm³ of 0.1 M NaCl. The molarity of the mixture is:
Q7. A 1 kg sample of water contains 0.002 g of lead. The concentration of lead in parts per million (ppm) is:
Q8. At a certain temperature, p°(benzene) = 100 torr and p°(toluene) = 40 torr. For an ideal equimolar mixture, the mole fraction of benzene in the vapour is about:
Q9. 1.8 g of a non-electrolyte in 100 g of water raises the boiling point by 0.052 K (Kb = 0.52 K kg mol⁻¹). The molar mass of the solute is:
Q10. Assuming complete dissociation, a 0.1 m aqueous CaCl₂ solution freezes at about (Kf = 1.86 K kg mol⁻¹):
Q11. Which 0.1 m aqueous solution has the highest boiling point (assume complete dissociation)?
Q12. Colligative properties of a dilute solution depend on:
Q13. The oxidation number of oxygen in OF₂ is:
Q14. The oxidation number of chromium in the dichromate ion, Cr₂O₇²⁻, is:
Q15. In the reaction 3Cl₂ + 6NaOH(hot, conc.) → 5NaCl + NaClO₃ + 3H₂O, the oxidation number of chlorine changes from 0 to:
Q16. In acidic solution MnO₄⁻ oxidizes oxalate ions: 2MnO₄⁻ + 5C₂O₄²⁻ + 16H⁺ → 2Mn²⁺ + 10CO₂ + 8H₂O. How many moles of CO₂ are produced per mole of MnO₄⁻ consumed?
Q17. In the electrolysis of concentrated aqueous NaCl with inert electrodes, the products at the cathode and anode are respectively:
Q18. Aqueous CuSO₄ is electrolysed using copper electrodes. Which statement is correct?
Q19. What mass of copper is deposited from CuSO₄ solution by 0.5 faraday of charge (Cu = 63.5)?
Q20. What volume of O₂ at STP is liberated at the anode by 1 faraday of charge during electrolysis of acidified water?
Q21. A current of 2 A is passed through AgNO₃ solution for 965 s. The mass of silver deposited is (Ag = 108, 1 F = 96500 C):
Q22. The same quantity of electricity is passed through AgNO₃ and CuSO₄ solutions in series. If 1.08 g of Ag is deposited, the mass of Cu deposited is (Ag = 108, Cu = 63.5):
Q23. Given E°(Ni²⁺/Ni) = −0.25 V and E°(Cu²⁺/Cu) = +0.34 V, the standard emf of the cell Ni | Ni²⁺ || Cu²⁺ | Cu is:
Q24. Silver nitrate solution should not be stored in a copper vessel because (E°: Cu²⁺/Cu = +0.34 V, Ag⁺/Ag = +0.80 V):
Q25. The salt bridge of a galvanic cell is usually filled with KCl or KNO₃ in agar gel because:
Q26. Which of the following is a rechargeable (secondary) cell?
Q27. The electrical conductance of an aqueous electrolyte solution increases with temperature mainly because:
Q28. An aqueous solution of NH₄Cl is acidic because:
Q29. Hydrogen peroxide reacts as H₂O₂ + 2I⁻ + 2H⁺ → I₂ + 2H₂O. In this reaction H₂O₂ acts as:
Q30. Which statement about an electrolytic cell is correct?