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

Answers (1)
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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