Atoms and Molec...

Molecular mass of  $${ Na }_{ 2 }{ SO }_{ 4 }$$ . $$10{ H }_{ 2 }O$$ is:

Which of the following is the best example of law of conservation of mass?

If Avogadro's number would have been $$1\times { 10 }^{ 23}$$, instead of $$6.02\times { 10 }^{ 23 }$$ then mass of one atom of $$_8^{16}O$$ would be:

Assertion: For the formation of a molecule at least two atoms are needed.
Reason: Molecules are formed by bonding between different atoms of different elements or complexes without any exception.

How many moles of helium gas occupy $$22.4L$$ at $$0^\circ C$$ at $$1$$ atm pressure?

$${ K }_{ 4 }\left[ Fe\left( CN \right) _{ 6 } \right]$$ is supposed to be $$40$$ percent dissociated when $$1M$$ solution prepared. Its boiling point is equal to another $$20$$ percent mass by volume of non-electrolytic solution $$A$$ Considering molality=molarity . The molecular weight of $$A$$ is: 

The ratio of radius of the nucleus to the radius of the atom is of the order:

A mixture of $$3\times10^{21}$$ molecules of $$X$$ and $$4.5\times10^{21}$$ molecules of $$Y$$ weigh $$1.375\ g$$. If the molecular weight of $$X$$ is $$50\ g$$, then what is the molecular weight of $$Y$$?

A box measures $$10\ cm \times 11.2\ cm \times 10\ cm$$. Assume that this box is filled with neon gas at $$1$$ atm pressure and $$273\ K$$ temperature. How many electrons will be there in the box ?