Exam: TOEFL

Definition: A colorless and flammable gas that is the lightest and most abundant element in the universe, often used in various chemical processes and fuels.

Example: Hydrogen is used in fuel cells to produce electricity.

Definition: A type of enzyme found in some microorganisms that helps in chemical reactions involving hydrogen, either by breaking down substances or by using hydrogen gas.

Example: The hydrogenase enzyme plays a crucial role in the energy metabolism of certain bacteria.

Definition: To combine a substance with hydrogen, often to change its chemical structure, such as turning liquid oils into solid fats.

Example: The process to hydrogenate vegetable oils makes them more stable for cooking.

Definition: Describing a substance that has been treated with hydrogen, often used to refer to fats that have been made more solid by adding hydrogen to them.

Example: Many processed foods contain hydrogenated oils that can affect health.

Definition: To treat a substance with hydrogen, often to make it more stable or to change its properties, especially in the context of fats and oils.

Example: The oil was hydrogenated to improve its shelf life and texture.

Definition: A chemical process where hydrogen is added to another substance, often to convert unsaturated compounds into saturated ones, typically using heat, pressure, and catalysts.

Example: The hydrogenation of vegetable oils makes them solid at room temperature.

Definition: Relating to or containing hydrogen.

Example: Water is a hydrogenous compound made up of hydrogen and oxygen.

Definition: A person who studies the distribution and movement of groundwater in the soil and rocks of the Earth's crust.

Example: The hydrogeologist conducted tests to determine the water quality in the area.

Definition: The study of how water interacts with the earth, focusing on groundwater and its movement, distribution, and effects.

Example: Hydrogeology is essential for understanding how to manage water resources effectively.

Definition: A scientist who studies and maps bodies of water, including oceans, rivers, and lakes.

Example: The hydrographer collected data to create accurate maps of the underwater terrain.

Definition: Related to the study and mapping of bodies of water, including their features like depth and flow.

Example: The hydrographic survey provided important data for the new shipping route.