Atoms and Molec...

Which of the following has the highest mass? 

If the molecular mass of a compound is $$74.5$$ then the compound is:

A sample of $${ CaCO }_{ 3 }$$ has $$Ca=40$$%, $$C=12$$% and $$O=48$$%. If the law of constant proportion is true then the weight of calcium in $$5g$$ of a sample of $${ CaCO }_{ 3 }$$ from another source will be:

Total no. of atoms in $$44\ g$$ of $$CO_{2}$$ is:

In an experiment reproducing the measurements of Rutherford and his co-workers, $$22 \times 10^{-3}$$ mg of He gas was collected in one year from a sample of radium. This sample was observed to emit $$1.06 \times 10^{11} \alpha$$ - particles per second. Thus, Avogadro's number is?

Find number of oxygen atoms present in $$100 \ mg$$ of $$CaCO_3$$.
(Atomic Mass of $$Ca=40 \ u, \ C=12 \ u, \ O=16 \ $$)

A compound contains 3.2% of oxygen. The minimum molecular weight of the compound is:

Haemoglobin contains $$4.6\%$$ of iron by mass. If the compound contains a single atom of iron then what is its molar mass in $$ { g\ mol }^{ -1 }$$?

Which of the following contains the largest mass of hydrogen atoms?

A solution of 0.640 g of azulene in 100.0 g of benzene boils at $$80.23^0C$$. The boiling point of benzene is $$80.10^0C$$; the $$K_b$$ is $$ 2.53^0C/molal$$. What is the molecular weight of azulene?