An organic compound contains 78% (by wt.) carbon and remaining percentage of hydrogen. The right option for the empirical formula of this compound is : [Atomic wt. of C is 12, H is 1]

The correct option for the empirical formula of the compound is CH₃.

To determine the empirical formula of an organic compound from the mass percentage of its constituent elements, we can follow a step-by-step approach based on mole ratios.

Step 1: Determine the mass percentage of each element
Given:
Percentage of Carbon (C) = 78%
Percentage of Hydrogen (H) = 100% - 78% = 22%

Assuming a 100 g sample of the organic compound, the mass of each element present in the sample would be:
Mass of Carbon (C) = 78 g
Mass of Hydrogen (H) = 22 g

Step 2: Calculate the number of moles of each element
The number of moles of an element is given by the formula:
Moles = Mass / Atomic Weight

Given atomic weights: Carbon (C) = 12, Hydrogen (H) = 1

Moles of Carbon (C):

$\text{Moles of C}=\frac{78}{12}=6.5$

Moles of Hydrogen (H):

$\text{Moles of H}=\frac{22}{1}=22$

Step 3: Determine the simplest mole ratio
To find the simplest whole-number molar ratio of the elements, divide the number of moles of each element by the smallest number of moles obtained (which is 6.5 for Carbon):

Ratio for Carbon (C):

$\text{C}=\frac{6.5}{6.5}=1$

Ratio for Hydrogen (H):

$\text{H}=\frac{22}{6.5}\approx 3.38\approx 3$

Rounding off to the nearest simplest whole number ratio, we get:
Carbon (C) : Hydrogen (H) = 1 : 3

Step 4: Write the empirical formula
Combining the elements with their simplest whole-number ratio gives the empirical formula as CH₃.