Atoms and Molec...

A diatomic molecule is :

The number of nitrogen atoms in $$21$$ g of nitrogen are:

Which of the following is a suitable example for illustrating the law of conservation of mass? (Atomic mass of O = 16 u; H = 1 u)

The molecular mass of $$CuSO_4.5H_2O$$ is:

Which has a higher mass : 1 mole of $$CO_2$$ or 1 mole of $$CO?$$ (Mass of $$C=12,$$  Mass of $$O=16$$)

The molecular mass of $$(NH_4)_2CO_3$$ is:

Sodium chloride ($$NaCl$$) reacts with silver nitrate ($$AgNO_3$$) to produce silver chloride ($$AgCl$$) and sodium nitrate ($$NaNO_3$$). The law which satisfies this equation is ___________________ .

A monoatomic element is:

Two chemical species $$X$$ and $$Y$$ combine together to form a product $$P$$ which contains both $$X$$ and $$Y$$

Consider the following statements:
(a) Molecular mass of $$CH_3OH$$ is $$32\ u.$$
(b) In $$NH_3$$, the ratio of $$N$$ and $$H$$ by mass is $$14: 3.$$
(c) The formula mass of $$CaCl_2$$ is $$ 111\ u.$$
(d) Isotopes have same mass number.