Question

The following data are obtained when dinitrogen and dioxygen react together to form different compounds :

	Mass of dinitrogen	Mass of dioxygen
(i)	14g	16g
(ii)	14g	32g
(iii)	28g	32g
(iv)	28g	80g

(a) Which law of chemical combination is obeyed by the above experimental data? Give its statement.

(b) Fill in the blanks in the following conversions:
(i) 1 km = mm = pm
(ii) 1 mg = kg = ng
(iii) 1 mL = L = ${dm}^3$

Answer 1

(a) When the mass of dinitrogen is 28g , mass of dioxygen combined is 32,64,32, and 80 g . The corresponding ratio is 1:2:1:5. It is a simple whole number ratio .
This illustrates the law of multiple proportions.
It states that, "if two elements can combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element, are in the ratio of small whole numbers.

(b) (i) $1km=1000m\times 100cm\times 10mm$

$\therefore 1km={10}^{6}mm$

$1km=1000m\times \frac{1pm}{{10}^{-12}m}$

$\therefore 1km={10}^{1}5pm$

Hence, $1km={10}^{6}mm={10}^{15}pm$

(ii) $1mg={10}^{-6}kg={10}^{6}ng$

(iii) $1ml={10}^{-3}l={10}^{-3}d{m}^3$