# 1.21    The following data are obtained when dinitrogen and dioxygen react together to form different compounds:                         Mass of dinitrogen                 Mass of dioxygen                             (i) 14 g                                              16 g                             (ii) 14 g                                             32 g                             (iii) 28 g                                            32 g                             (iv) 28 g                                            80 g        (b) Fill in the blanks in the following conversions:                     (i) 1 km = ...................... mm = ...................... pm                     (ii) 1 mg = ...................... kg = ...................... ng                     (iii) 1 mL = ...................... L = ...................... dm3

D Divya Prakash Singh

(i) As we know in $1km = 1000m$ or  $1m = 1000mm$.  or  $1 km = 1000\times1000 mm =10^6 mm$

And  $1pm = 1\times10^{-12}m$   or   $1km = 10^{15} pm$

Therefore we have,

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

(ii) As we know in $1kg = 1000g$ or  $1g = 1000mg$.  or  $1 kg = 1000\times1000 mg$   or   $1mg = \frac{1}{10^6} kg=10^{-6}kg$

And  $1 ng = 10^{-9}g$   or   $1ng = 10^{-9}\times1000mg$   or   $1ng = 10^{-6}mg$

or   $1 mg =10^6ng$.

Therefore we have,

$1 mg = 10^{-6} kg =10^{6} ng$.

(iii) As we know in $1L= 1000mL$ or  $1mL =\frac{1}{1000}L = 10^{-3}L$

or  $1dm = 0.1 m \Rightarrow 1dm = 10cm$   or   $1cm = 0.1dm$

And $1mL = 1cm^3$  or we can write it as: $1mL = \frac{1dm}{10cm}\times\frac{1dm}{10cm}\times\frac{1dm}{10cm}$

And  $1mL = 10^{-3}dm^3$

Therefore we have,

$1mL = 10^{-3}L =10^{-3}dm^3$

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