Covalent compounds can be subdivided into polar and no polar compounds. In water, a polar molecule, the hydrogen electrons are not shared equally with the oxygen atoms; this results in a polar bond. Oxygen due to it's greater electro negativity pulls the electrons closer to its nucleus.
The Treaty of Versailles was the main causes of World War II due to the following reasons,Germany had to pay back 33 billion after WWI and forced to accept sole blame for the war in order to justify the reparations.
The  treaty also prevented Germany from uniting with Austria. It made  Germany very poor.    Here are the terms of the Treaty of Versailles:   Germany was to accept the blame for starting the war, under the  terms of 'War guilt' cause.  Germany was to reduce its army to 100,000 men.