Explanation

Citric acid is a natural preservative and flavoring agent that is commonly used in foods and beverages to add a sour taste.

It is particularly useful in cold drinks, such as:

• Soft drinks (e.g., lemon-lime soda)
• Fruit juices (e.g., orange, grapefruit)
• Sports drinks
• Energy drinks

Explanation

Potassium hydroxide (KOH) is used to make soft soaps, which are typically more soluble and have a lower melting point than soaps made with sodium hydroxide (NaOH).

Soft soaps are often used in liquid soaps, shampoos, and body washes.

Explanation

The carboxylate end of a soap molecule (-COO-) is hydrophilic (water-loving), meaning it is attracted to water.

This end of the molecule is negatively charged and is able to form hydrogen bonds with water molecules, which are polar and also have a slightly positive charge.

Explanation

Surfactants reduce the surface tension of water, which is the energy required to create a surface between water and air.

By reducing surface tension, surfactants make it easier for water to spread and penetrate surfaces, which is important for cleaning and other applications.

Explanation

Soap is a type of salt that is formed from the reaction of a fatty acid with an alkali, such as sodium or potassium hydroxide.

Fatty acids are long-chain carboxylic acids that are found in fats and oils.

Explanation

Spectroscopy is a analytical technique used to measure the interaction between matter and electromagnetic radiation, such as light.

It is used to assess the concentration or amount of a given atomic, molecular, or ionic chemical species by measuring the absorption, emission, or scattering of light by the species.

Explanation

In gas chromatography (GC), the mobile phase is a gas, such as helium, nitrogen, or argon, that carries the sample through the column.

The sample is vaporized and separated based on its affinity for the stationary phase, which is typically a solid or liquid coating on the column.

Explanation

Spectroscopy is the study of the interaction between light (electromagnetic radiation) and matter.

This interaction can occur with atoms, molecules, or ions in any state (solid, liquid, gas, or plasma).

Explanation

Accuracy refers to how close a measured value is to the true or accepted value.

It indicates the degree of agreement between the measured value and the true value.

Explanation

Systematic errors are caused by faulty or improper functioning of instruments, or by a flaw in the experimental design.

These errors are consistent and repeatable, and can be identified and corrected.