The empirical formula of a compound represents the simplest ratio of atoms present in the compound. In order to determine the molecular formula, we need to know the molecular mass of the compound.

Given:
Empirical formula = CH2Cl
Molecular mass = 99 g

To find the molecular formula, we need to determine the actual number of atoms of each element in the compound.

Step 1: Calculate the empirical formula mass
The empirical formula mass can be calculated by adding up the atomic masses of all the atoms in the empirical formula.

Empirical formula mass = (1 * atomic mass of C) + (2 * atomic mass of H) + (1 * atomic mass of Cl)
Empirical formula mass = (1 * 12.01 g/mol) + (2 * 1.01 g/mol) + (1 * 35.45 g/mol)
Empirical formula mass = 12.01 g/mol + 2.02 g/mol + 35.45 g/mol
Empirical formula mass = 49.48 g/mol

Step 2: Calculate the empirical formula factor
The empirical formula factor is the ratio of the molecular mass to the empirical formula mass.

Empirical formula factor = Molecular mass / Empirical formula mass
Empirical formula factor = 99 g / 49.48 g/mol
Empirical formula factor = 2

Step 3: Multiply the subscripts in the empirical formula by the empirical formula factor
Multiply the subscript of each element in the empirical formula by the empirical formula factor to obtain the subscripts in the molecular formula.

Molecular formula = (C1 * empirical formula factor) + (H2 * empirical formula factor) + (Cl1 * empirical formula factor)
Molecular formula = (C1 * 2) + (H2 * 2) + (Cl1 * 2)
Molecular formula = C2H4Cl2

Therefore, the molecular formula of the compound with the empirical formula CH2Cl and a molecular mass of 99 g is C2H4Cl2, which corresponds to option A.