A partially dried clay mineral contains 8% water. The original sample contained 12% water and 45% silica. The percentage of silica  in the partially dried sample is nearly:

1. 50%

2. 49%

3. 55%

4. 47%

One litre N₂, 7/8 litre O₂ and 1 litre CO are taken in a mixture under indentical conditions of P and T. The amount of gases present in mixture is given by:

1. ${\mathrm{\omega }}_{{\mathrm{N}}_2}={\mathrm{\omega }}_{{\mathrm{O}}_2}>{\mathrm{\omega }}_{\mathrm{CO}}$ 

2. ${\mathrm{\omega }}_{{\mathrm{N}}_2}={\mathrm{\omega }}_{\mathrm{CO}}>{\mathrm{\omega }}_{{\mathrm{O}}_2}$ 

3. ${\mathrm{\omega }}_{{\mathrm{N}}_2}={\mathrm{\omega }}_{{\mathrm{O}}_2}={\mathrm{\omega }}_{\mathrm{CO}}$

4. ${\mathrm{\omega }}_{\mathrm{CO}}>{\mathrm{\omega }}_{{\mathrm{N}}_2}>{\mathrm{\omega }}_{{\mathrm{O}}_2}$

Equal volumes of 0.1 M AgNO₃ and 0.2 M NaCl are mixed. The concentration of N${\mathrm{O}}_3^{-}$ ions in the mixture will be:

1. 0.1M

2. 0.05M

3. 0.2M

4. 0.15M

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

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.$\approx$6.5 

2.$\approx$6.9

3. $\approx$7.6

4. $\approx$7.9

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

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

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

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 these

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