Question

(i) What is Relative molecular mass.

(ii) Calculate the relative molecular mass of Na2

CO3

.10H2O [Na = 23, O = 16, C =12, H =1]​

Answer 1

Answer:

the sum of all the relative atomic masses of the atoms in a molecule; the ratio of the average mass per molecule of a specified isotopic composition of a substance to one-twelfth the mass of an atom of carbon-12Symbol: M r Abbreviation: r.m.m

2)Na2CO3.10H2O=3*16+10*16=208 g

Since, 1 mole of Na2CO3.10H2O contain Oxygen= 208 g

hence, 0.1 mole of Na2CO3.10H2O contain Oxygen= 208*0.1=20.8 g

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Answer 2

Answer

i) the ratio of the average mass of one molecule of an element or compound to one twelfth of the mass of an atom of carbon 12

ii) 23×2 + 12×1 + 16×3 + 10(2×1 + 16×1)

= 46 + 12 + 48 + (10×18)

=106 + 180

= 286