Which of the following samples will react fastest with dilute trioxonitrate (V) acid?
- A. 5 g of lumps of CacO3 at 25°C
- B. 5 g of powered CacO3 at 25°
- C. 5 g of lumps of CaCO3 at 50°C
- D. 5 g of powered CaCO3 AT 50°C
Iron galvanized with zinc is cathodically protected from corrosion. This is because?
- A. zinc has a more positive oxidation potential than iron
- B. zinc has less positive oxidation potential than iron
- C. bith have the same oxidation potential
- D. zinc is harder than iron
Fe\(_2\)O\(_{3(s)}\) + 2Al\(_{(s)}\) → Al\(_2\)O\(_3\) + 2Fe\(_{(s)}\). If the heats of formation of Al\(_2\)O\(_3\) and Fe\(_2\)O\(_3\) are – 1670 kJmol\(^{-1}\) and – 822 kJmol\(^{-1}\) respectively, the enthalpy change in kJ for the reaction is ?
- A. +2492
- B. +848
- C. -848
- D. -2492
In the reaction 1O–3 + 5l– + 6H+ → 312 + 3H2O, the oxidizing agent is?
- A. H+
- B. l-
- C. 1O-
- D. l2
Cr2O7 + 6Fe2+ + 14H+ → 2Cr3+ +6Fe3+ + 7H2O. In the above , the oxidation number of chromium changed from?
- A. +7 to +3
- B. +6 to +3
- C. +5 to +3
- D. -2 to +3
In a reaction: \(SnO_{2} + 2C → Sn + 2CO\) the mass of coke containing 80% carbon required to reduce 0.302 kg of pure tin oxide is?
(Sn – 119, O – 16, C – 12).
- A. 0.40 kg
- B. 0.20 kg
- C. 0.06 kg
- D. 0.04 kg
Which of the following is a physical change?
- A. The bubbling of chlorine into water
- B. The bubbling of chlorine into a jar contanining hydrogen
- C. The dissolution of sodium chloride in water
- D. The passing of steam over heated iron