To determine the formula for the hydrocarbon CxHy, we can start by calculating the percentage composition of carbon and hydrogen in the compound using the given data.

Given:
W(C) = 83.7%
D(O2) = 2.69

Step 1: Calculate the percentage of oxygen in the compound

%O = 100% - %C = 100% - 83.7% = 16.3%

Step 2: Calculate the moles of carbon, hydrogen, and oxygen in the compound

Let the moles of C = x
Moles of O = 2.69/32 [Molar mass of oxygen] = 0.084 moles

Since the compound is a hydrocarbon,
Moles of H = x*2

Step 3: Convert moles to mass
Mass of C = x12 [molar mass of carbon]
Mass of H = 2x1 [molar mass of hydrogen]
Mass of O = 0.084*16 [molar mass of oxygen]

Step 4: Calculate the mass percentages of C, H, and O in the compound
%C = (Mass of C / Total mass of compound) 100
%C = (12x / (12x + 2x + 0.08416)) 100
%C = (12x / (14x + 1.344)) 100

%H = (Mass of H / Total mass of compound) 100
%H = (21 / (12x + 2x + 0.08416)) 100
%H = (2 / (14x + 1.344)) * 100

%O = (Mass of O / Total mass of compound) 100
%O = (0.08416 / (12x + 2x + 0.08416)) 100
%O = (1.344 / (14x + 1.344)) * 100

Step 5: Set up the equations based on the given data

%C = 83.7% => (12x / (14x + 1.344)) 100 = 83.7
%H = => (2 / (14x + 1.344)) 100 = ?
%O = 16.3% => (1.344 / (14x + 1.344)) * 100 = 16.3

Step 6: Solve for x

From the equation:
(12x / (14x + 1.344)) * 100 = 83.7
12x = 83.7(14x + 1.344)

This equation can be solved to find the value of x, which will give us the subscripts for C and H in the compound CxHy.