The percentage of oxygen present in the compound ${\mathrm{CaCO}}_3.3{\mathrm{Ca}}_3<mspace\; width="1em"></mspace>{\left({\mathrm{PO}}_4\right)}_2$ is-

1.  23.3%

2.  45.36%

3.  41.94%

4.  17.08%

A gaseous compound is composed of 85.7% by mass carbon and 14.3% by mass hydrogen. It's density is 2.28 g/litre at 300 K and 1.0 atm pressure. Determine the molecular formula of the compound:

1.  ${\mathrm{C}}_2{\mathrm{H}}_2$

2.  ${\mathrm{C}}_2{\mathrm{H}}_4$

3.  ${\mathrm{C}}_4{\mathrm{H}}_8$

4.  ${\mathrm{C}}_4{\mathrm{H}}_{10}$

Calculate the % of free ${\mathrm{SO}}_3$ in oleum (a solution of ${\mathrm{SO}}_3$ in ${\mathrm{H}}_2{\mathrm{SO}}_4$) that is labelled 109% ${\mathrm{H}}_2{\mathrm{SO}}_4$.

1. 40

2. 30

3. 50

4. None

Suppose two elements X and Y combine to form two compounds ${\mathrm{XY}}_2$ and ${\mathrm{X}}_2{\mathrm{Y}}_3$when 0.05 mole of${\mathrm{XY}}_2$ weighs 5 g while 3.011$\times$10²³ molecules of ${\mathrm{X}}_2{\mathrm{Y}}_3$ weighs 85 g. The atomic masses of x and y are respectively:

1.  20, 30

2.  30, 40

3.  40, 30

4.  80, 60

100 mL of 10% NaOH (w/V) is added to 100 mL of 10% HCl (w/V). The resultant solution becomes:

1. Alkaline

2. Strongly alkaline

3. Acidic

4. Neutral

1.44 gram of titanium (At. wt. =48) reacted with excess of ${\mathrm{O}}_2$ and produce x gram of non-stoichiometric compound ${\mathrm{Ti}}_{1.44}<mspace\; width="1em"></mspace>\mathrm{O}.$ The value of x is:

1.  2

2.  1.77

3.  1.44

4.  None of the above

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

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%

The vapour density of a mixture containing \(NO_{2}\) and \(N_{2} O_{4}\)  is 38.3. The mole of \(NO_{2}\) 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