Exam: TOEFL

Definition: A special metal made from nickel and titanium that can change shape when heated and return to its original form.

Example: The doctor used a nitinol stent to help keep the artery open after surgery.

Definition: A chemical compound that contains the nitrate ion, which is made up of one nitrogen atom and three oxygen atoms. Nitrates are often found in fertilizers and can also occur in some foods and water.

Example: Farmers often use nitrate fertilizers to help their crops grow better.

Definition: To treat a substance with nitric acid or a nitrate, often to convert it into a nitrate compound.

Example: The chemist decided to nitrate the organic material to enhance its properties.

Definition: Describes a substance that has undergone a chemical reaction with nitric acid or a nitrate, often resulting in the addition of nitrate groups to the compound.

Example: The nitrated compound is used in various industrial applications due to its enhanced properties.

Definition: The process of introducing a nitro group into an organic compound, typically through a reaction with nitric acid and often in the presence of sulfuric acid.

Example: Nitration is commonly used in the production of explosives and dyes.

Definition: Relating to or containing nitrogen, particularly in a higher oxidation state than in similar compounds.

Example: Nitric acid is commonly used in fertilizers and explosives.

Definition: A chemical compound that includes nitrogen and another element that is more positive in charge, like a metal or phosphorus.

Example: Silicon nitride is often used in high-performance ceramics.

Definition: To treat a material, especially steel, so that nitrogen is absorbed into its surface to make it harder.

Example: The engineers decided to nitride the steel components to improve their durability.

Definition: The process in which certain bacteria convert ammonia into nitrites and then into nitrates, which are forms of nitrogen that plants can use.

Example: Nitrification is an important step in the nitrogen cycle, helping to make nutrients available to plants.

Definition: A type of bacteria that helps convert ammonia into nitrates in the soil, playing a key role in the nitrogen cycle.

Example: Nitrifiers are essential for healthy soil as they help plants access nutrients.

Definition: To convert ammonia or its compounds into nitrates or nitrites, often through a biological process involving bacteria.

Example: Farmers often nitrify the soil to enhance its nutrient content for better crop growth.

Definition: Relating to bacteria that convert ammonia into nitrite and nitrate in the soil, playing a key role in the nitrogen cycle.

Example: Nitrifying bacteria are essential for healthy soil and plant growth.