Asample of a hydrocarbon contains 20.75 g c and 4.25 g h . it’s molar mass is 58.04 g/mol . what is its empirical formula

From the periodic table:
AMU Carbon = 12 g/mol
AMU Hydrogen = 1 g/mol

Given:
20.75 g C
4.24 g H

20.75 g × 1mol/12g C = 1.73 mole C
4.25 g × 1mol/1.008g H = 4.22 mol H

Mole ratio's: (divide by smallest mole present)

1.73 mol C / 1.73 mol C = 1 Carbon
4.22 mol H / 1.73 mol C = 2.44 Hydrogen

Since, 2.44 Hydrogen is close to 2.; multiply both by 2 to get a whole number. Also the pairing of 1 carbon  + 2 hydrogen doesn't work.

Empirical Formula =

Since you are given atomic mass of the compound, you can also determine the Molecular formula .
AMU of empirical = 2(12) + 5(1.008) = 29.04 g/mol

58.04 g/mol actual compound / 29.04 g/mol empirical = 2
double everything again to get the actual molecular formula

Where are the following questions

The net force is 100