what is an organic compound that has the ratio of H:O = 2:1?

All carbohydrates, including all monosaccharides (C₆H₁₂O₆), disaccharides (C₁₂H₂₂O₁₁) and polysaccharides (C₆(H₂O)₅n), have the mole ratio H : O = 2 : 1.

Also, my other compounds (such as methanal (HCHO), acetic acid (CH₃COOH), propanedial (CH₂(CHO)₂), etc.) have the mole ratio H : O = 2 : 1.

Water is not considered organic. Simplest organic with that ratio is Formaldehyde, CH2O.

Carbohydrates has a carbon:hydrogen:oxygen ratio of 1:2:1.
For example: Glucose (C6H12O6)

C₂H₄O₂

The combined ratio of H : O can not be termed as organic compound because the basic element CARBON is missing. Your chemical formula indicates that when when 2 atoms of hydrogen combines with 1 atom of oxygen the result is a molecule of WATER.

H2O is water, not organic.

Organic compounds are derivatives of carbon and hydrogen.

According to the given ratio.

Compound is H2O but it cannot be treated as an organic one.

CH2O

water?

Water.

Dihydrogen Monoxide ( H2O) commonly known as 'WATER'.