2.0 g sample contain mixture of ${\mathrm{SiO}}_2$ and ${\mathrm{Fe}}_2{\mathrm{O}}_3$, on very strong heating leave a residue weighing 1.96 g. The reaction responsible for loss of weight is ${\mathrm{Fe}}_2{\mathrm{O}}_3 \left(\mathrm{s}\right) \stackrel{}{\to } {\mathrm{Fe}}_3{\mathrm{O}}_4 \left(\mathrm{s}\right) + {\mathrm{O}}_2 \left(\mathrm{g}\right)$ (unbalance equation)

What is the percentage by mass of ${\mathrm{SiO}}_2$ in original sample?

1.  10%

2.  20%

3.  40%

4.  60%

For the reaction; 
\(2Fe{(NO_3)}_3 + 3Na_2CO_3 \rightarrow Fe_2{(CO3)}_3 + 6NaNO_3\)
Initially if 2.5 mole of \(Fe{(NO_3)}_3 \) and 3.6 mole of \(Na_2CO_3\) is taken. If 6.3 mole of \(NaNO_3\) is obtained then % yield of given reaction is:

1.  50

2.  84

3.  87.5

4.  100

0.8 mole of a mixture of CO and CO₂ requires exactly 40 gram of NaOH in a solution for complete conversion of all the CO₂ into Na₂CO₃. How many moles more of NaOH would it require for conversion into Na₂CO₃, if mixture (0.8 mole) is completely oxidised to CO₂?

1.  0.2

2.  0.6

3.  1

4.  1.5

The impure 6 g of $\mathrm{NaCl}$ is dissolved in water and then treated with excess of silver nitrate solution. The weight of precipitate of silver chloride is found to be 14 g. The % purity of $\mathrm{NaCl}$ solution would be:

1.  95%

2.  85%

3.  75%

4.  65%

25.4 g of ${\mathrm{I}}_2$ and 14.2 g  of ${\mathrm{Cl}}_2$ are made to react completely to yield a mixture of ICI and ICI₃. The mole of ICI and ICI₃ formed, is respectively -

1. 0.5, 0.2

2. 0.1, 0.1

3. 0.1, 0.3

4. 0.3, 0.4

The vapour density of a mixture containing ${\mathrm{NO}}_2$ and ${\mathrm{N}}_2{\mathrm{O}}_4$  is 38.3. The mole of ${\mathrm{NO}}_2$ in a 100 g mixture is:

[Vapour density = (Molar mass / 2)]

1. 0.437

2. 0.347

3. 0.557

4. 0.663

Copper forms two oxides. For the same amount of copper, twice as much oxygen was used to form first oxide than to form second one. What is the ratio of the valencies of copper in first and second oxides?

1. 2:5

2. 1:6

3. 2:1

4. 1:2

5 mL of a gaseous hydrocarbon was exposed to 30 mL of ${\mathrm{O}}_2$. The resultant gas, on cooling is found to measure 25 mL of which 10 mL is absorbed by NaOH and the remainder by pyrogallol. Determine molecular formula of hydrocarbon. All measurements are made at constant room temperature.

1. CH₄

2. C₂H₂

3. C₃H₄

4.C₂H₄

60 mL of a mixture of nitrous oxide and nitric oxide was exploded with excess of hydrogen. If 38 mL of ${\mathrm{N}}_2$ was formed, calculate the volume of each gas in the mixture. All measurements are made at constant P and T.

1.20 ml +30 ml

2. 44 ml + 16 ml

3. 10 ml+40 ml

4 .25 ml +25 ml

2.0 g sample containing ${\mathrm{Na}}_2{\mathrm{CO}}_3$and ${\mathrm{NaHCO}}_3$ loses 0.248 g when heated to 300$°$C, the temperature at which ${\mathrm{NaHCO}}_3$ decomposes to ${\mathrm{Na}}_2{\mathrm{CO}}_3$, ${\mathrm{CO}}_2$ and ${\mathrm{H}}_2\mathrm{O}$. What is the % of ${\mathrm{Na}}_2{\mathrm{CO}}_3$ in mixture?

1.66.5

2.50.6

3.60.5

4.6.65