Let's analyze each statement:

• A) Double bond is shorter than a single bond: This statement is correct. As the number of bonds between two atoms increases, the bond length decreases. A double bond involves sharing of four electrons, leading to greater attraction and shorter bond length compared to a single bond (sharing of two electrons).
• C) Double bond is stronger than a single bond: This statement is correct. A double bond has a higher bond energy than a single bond between the same two atoms, meaning more energy is required to break it. This is due to the presence of both a sigma ($\sigma$) and a pi ($\pi$) bond in a double bond, making it stronger than a single bond (which only has a sigma bond).
• D) Covalent bond is stronger than hydrogen bond: This statement is correct. Covalent bonds are intramolecular forces (forces within a molecule) and are generally much stronger (bond energies typically in the range of 150-1100 kJ/mol) than intermolecular forces like hydrogen bonds (bond energies typically in the range of 10-40 kJ/mol). Hydrogen bonds are responsible for interactions between molecules.
• B) This option is empty and therefore cannot be evaluated as a correct or incorrect statement. In a multiple-choice question, an empty option is typically considered incorrect or invalid if it were to be chosen as the answer to a 'correct statement' question. However, since the question asks for an 'incorrect statement' and options A, C, and D are all correct statements, the empty option B is the one that is not a correct statement, making it the 'incorrect' choice in the context of finding a statement that is not true.

Since options A, C, and D are all correct statements, and the question asks for the incorrect statement, the empty option B is the one that does not represent a correct chemical statement.

Correct Answer: (B)