A hydrated sodium sulphate salt, Na₂SO₄·nH₂O, loses 55% of its mass on heating to form anhydrous Na₂SO₄. What is the value of n?

1. Five (5) 2. Three (3)
3. Seven (7) 4. Ten (10)

Subtopic:  Empirical & Molecular Formula |
 54%
Level 3: 35%-60%
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The product of atomic mass and specific heat of metal is approximately 6.4. This was given by:

1. Dalton's law

2. Avogadro's law

3. Newton's law

4. Dulong Petit's law

Subtopic:  Introduction |
 62%
Level 2: 60%+
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A clay mineral initially contains 12% water and 45% silica by mass. If its water content is reduced to 8% by partial drying, what is the approximate percentage of silica in the dried sample?

1. 50% 2. 49%
3. 55% 4. 47%
Subtopic:  Concentration Based Problem |
Level 3: 35%-60%
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In the Haber process, 30 L of H₂ and 30 L of N₂ are allowed to react. If the reaction gives only 50% of the theoretically expected yield of NH₃, what will be the composition of the gaseous mixture at the end of the reaction?

1. 20 L ammonia, 10 L nitrogen, 30 L hydrogen

2. 10 L ammonia, 25 L nitrogen, 15 L hydrogen

3. 20 L ammonia, 20 L nitrogen, 20 L hydrogen

4. 20 L ammonia, 25 L nitrogen, 15 L hydrogen

Subtopic:  Limiting Reagent |
Level 4: Below 35%
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The mass of carbon anode consumed (giving only carbon dioxide) in the production of 270 kg of aluminium metal from bauxite by the Hall process is (at. mass of Al = 27)

1. 180 kg

2. 270 kg

3. 540 kg

4. 90 kg

Subtopic:  Equation Based Problem |
Level 3: 35%-60%
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What is the mole fraction of the solute in a 1.00 molal aqueous solution?

1. 0.00177 2. 0.0344
3. 0.0177 4. 0.1770
Subtopic:  Concentration Based Problem |
 51%
Level 3: 35%-60%
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2 gm Iron pyrite (FeS2) is burnt with O2 to form Fe2O3 and SO2. The mass of SO2 produced is (Fe=56, S=32, O=16)

1. 2 gm

2. 2.13 gm

3. 4 gm

4. 4.26 gm

Subtopic:  Equation Based Problem |
 70%
Level 2: 60%+
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Equivalent weight of FeS2 in the half reaction, FeS2→Fe2O3+SO2 is:

1.  M/10

2.  M/11

3.  M/6

4.  M/1

Subtopic:  Equivalent Weight |
 54%
Level 3: 35%-60%
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The equivalent weight of HCl in the given reaction is: K2Cr2O7+14HCl→2KCl+2CrCl3+3Cl2+H2O

1.  16.25

2.  36.5

3.  73

4.  85.1

Subtopic:  Equivalent Weight |
Level 4: Below 35%
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Equivalent weight of H3PO2 when it disproportionate into PH3 and H3PO3 is:

1. M

2. M/2

3. M/4

4. 3M/4

Subtopic:  Equivalent Weight |
Level 3: 35%-60%
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