1.9g of CHxBry has same no. of atoms as in 0.6g og H2O. The value of x+y is ?
 

Dear student

Here one needs to use the concept of the moles. According to the question, first we need to find the number of moles of water in 0.6 g.
As per the molar mass of water is 18g/mol so in 18g, we have 1 mol of water. So
$$\begin{gathered} in 0.6g we have \frac{0.6}{18}mol = 0.033 mol of water. \\ Also one mole of water has hydrogen atoms = 2 mol \\ so 0.033 mol of water have hydrogen = 2\times 0.033 = 0.0667 mol \\ similarly 1 mol of water has oxygen = 1 mol \\ thus 0.033 mol of water have oxygen = 0.033 mol \\ thus the total number of atoms in 0.6g of water are 0.033+0.0667 = 0.1 mol \\ In a similar way, one can find the molar mass of the given compound, \\ C = 12, H = 1 and Br 80g/mol \\ so the molar mass of the given compound will be 12+x+80y \\ thus 12+x+80y g of the compound has total number of atoms as (1+x+y) \end{gathered}$$
$$\begin{gathered} thus 1.9 g of the compound has total number of atoms as: \\ \frac{(1+x+y)(1.9)}{(12+x+80y)} \\ \sin ce this value can be taken as 0.1 mol \\ so on solving the equation will be \\ 18x+7-61y = 0 \\ by hit and trial method, if one puts x = 1, so y = (25/61) which is fraction so can not be considered. If x = 2, y = (43/61) again fraction so not correct \\ on putting x = 3, y =1 \\ so both x and y are integers here x \\ so x+y =3+1=4 \end{gathered}$$

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