A sample of pure Cu (3.18g ) heated in a stream of oxygen for some time gains in mass with the formation of black oxide of copper (CuO). The final mass is 3.92 g. The percent of copper remains unoxidised is-

1.6.5 

2.6.9

3. 7.6

4. 7.9

Subtopic:  Equation Based Problem |
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One mole of a mixture of CO and CO2 requires exactly 20g of NaOH in solution for the complete conversion of all the CO2 into Na2CO3. How much NaOH would it require for conversion into Na2CO3, if the mixture (one mole) is completely oxidised to CO2?

1. 60g

2. 80g

3. 40g

4. 20g

Subtopic:  Equation Based Problem |
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The mass  of 50% (w/w) solution of HCl required to react with 100g of CaCO3 would be:

(1) 73g

(2) 100g

(3) 146g

(4) 200g

Subtopic:  Equivalent Weight |
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Versene, a chelating agent having chemical formula C2H4N2(C2H2O2Na)4. If each mole of this compound could bind 1 mole of Ca2+, then the rating of pure versene expressed as mg of CaCO3 bound per g of chelating agent is:

1. 100 mg

2. 163 mg

3. 200 mg

4. 263 mg

Subtopic:  Equation Based Problem |
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A gas is found to have the formula (CO)x. Its VD is 70. The value of x must be:

1. 7 

2. 4

3. 5

4. 6

Subtopic:  Moles, Atoms & Electrons |
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When 100 mL of PH3 is decomposed, it produces phosphorus and hydrogen. The change in volume is:

1. 50  mL increase. 2. 500 mL decrease.
3. 900 mL decrease. 4. None of the above.

Subtopic:  Equation Based Problem |
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The molality of 1M solution of NaCl ( specific gravity 1.0585 g/mL ) is:

1. 1.0585

2. 1.0

3. 0.10

4. 0.0585

Subtopic:  Concentration Based Problem |
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The total molarity of all the ions present in  0.1 M of CuSO4 and 0.1 M of Al2(SO4)3 solution is:

1. 0.2M

2. 0.7M

3. 0.8M

4. 1.2M

Subtopic:  Concentration Based Problem |
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A solution contains Na2CO3 and NaHCO3. 10 mL of the solution required 2.5 mL of 0.1 M H2SO4 for neutralisation using phenolphthalein as indicator. Methyl orange is then added when a further 2.5 mL of 0.2 M H2SO4 was required. The amount of Na2CO3 and NaHCO3 in 1 litre of the solution is:

1. 5.3g and 4.2g

2. 3.3g and 6.2g

3. 4.2g and 5.3g

4. 6.2g and 3.3g

Subtopic:  Millimole/Equivalent Concept |
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Equal volumes of 0.1 M AgNO3 and 0.2 M NaCl are mixed. The concentration of NO3- ions in the mixture will be:

1. 0.1M 2. 0.05M
3. 0.2M 4. 0.15M

Subtopic:  Concentration Based Problem |
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