Average atomic mass of magnesium is 24.31 a.m.u. This magnesium is compound of 79 mole% of ${}_{24}\mathrm{Mg}$ and remaining 21 mole % of ${}_{25}\mathrm{Mg}$ and ${}_{26}\mathrm{Mg}$. Calculate mole% of ${}_{26}\mathrm{Mg}$.

1.  10

2.  11

3.  15

4.  16

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

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%

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

What is the number of iron atoms present in each molecule of hemoglobin if hemoglobin from the red blood cells of most mammals contains approximately 0.33% iron by mass, with a molecular mass of 67,200 amu? (Atomic mass of iron = 56)

1. 2

2. 3

3. 4

4. 5

Volume strength of 1 M solution of ${\mathrm{H}}_2{\mathrm{O}}_2$ is:

A 2 g sample of xenon reacts with fluorine. The mass Of compound produced is 3.158 g. The empirical formula of the compound is

1.  ${\mathrm{XeF}}_2$

2.  ${\mathrm{XeF}}_4$

3.  ${\mathrm{XeF}}_5$

4.  ${\mathrm{XeF}}_6$

1.625 g of an interhalogen compound ${\mathrm{ICI}}_{\mathrm{x}}$ was subjected to electric discharge which split it into constituents and brought to STP It occupied 224 ml. The interhalogen compound is

1.  ICl

2.  ${\mathrm{lCl}}_3$

3.  ${\mathrm{lCl}}_5$

4.  ${\mathrm{lCl}}_7$

A 10.0 g Of sample Of mixture of calcium chloride and sodium chloride is treated with ${\mathrm{Na}}_2{\mathrm{CO}}_3$ to precipitate the calcium as calcium carbonate. This ${\mathrm{CaCO}}_3$ is heated to convert all calcium to Cao and the final mass of Cao is 1.62 gms. The % by mass of CaC12 in the original mixture is

1.   15.2%

2.   32.1%

3.   21.8%

4.   11.07%