1.
Chemical reactions that absorb energy as they occur are called:
Correct Answer
B. Endothermic
Explanation
Endothermic reactions are chemical reactions that absorb energy from their surroundings as they occur. This energy is usually in the form of heat, and as a result, the temperature of the surroundings decreases. In an endothermic reaction, the products have more energy than the reactants, and the reaction requires an input of energy to proceed. This is in contrast to exothermic reactions, which release energy to the surroundings and typically result in an increase in temperature. Self-sustained and thermodynamic are not accurate descriptions of reactions that absorb energy.
2.
Chemical reactions that give off energy as they occur are called:
Correct Answer
A. Exothermic
Explanation
Exothermic reactions release energy as they occur. This means that the reactants have a higher energy level than the products, and the excess energy is released in the form of heat, light, or sound. In contrast, endothermic reactions absorb energy from their surroundings, resulting in a decrease in temperature. Self-sustained and thermodynamic are not accurate terms to describe reactions that give off energy.
3.
What is a chemical chain reaction that releases energy in the form of heat and light?
Correct Answer
B. Fire
Explanation
Fire is a chemical chain reaction that releases energy in the form of heat and light. It occurs when a flammable substance combines with oxygen in the presence of heat, resulting in the production of flames and the release of energy. Fire is commonly used for various purposes, such as heating, cooking, and providing light, but it can also be destructive if not controlled.
4.
What is the term used to define a chemical chain reaction involving combination of oxygen with other materials?
Correct Answer
A. Oxidation
Explanation
Oxidation is the term used to define a chemical chain reaction involving the combination of oxygen with other materials. This process results in the loss of electrons from the substance being oxidized. Combustion, convection, and radiation are not specifically related to the combination of oxygen with other materials.
5.
In the flamming mode of combustion, what type of fuel is required?
Correct Answer
B. Gaseous
Explanation
In the flaming mode of combustion, gaseous fuel is required. This is because in this mode, combustion occurs when the fuel vaporizes and mixes with oxygen in the air to form a flammable mixture. Gaseous fuels, such as natural gas or propane, are already in a vaporized state and easily mix with oxygen, allowing for efficient combustion and the production of a visible flame.
6.
What type of combustion is best described as solid fuel that is porous and charring on the surface?
Correct Answer
B. Smoldering
Explanation
Smoldering is the best description for solid fuel that is porous and charring on the surface. Smoldering combustion occurs when a solid material, such as wood or coal, burns slowly with a low flame or no visible flame at all. It is characterized by the fuel's surface charring and the release of smoke and gases. The porous nature of the fuel allows for slow, incomplete combustion, resulting in the smoldering process.
7.
The two key factors influencing the combustion process are the physical state of the fuel and its distribution or orientation.
Correct Answer
A. True
Explanation
The statement is true because the physical state of the fuel, such as whether it is in solid, liquid, or gaseous form, can greatly affect the combustion process. Different fuels have different combustion properties, and their physical state can determine how easily they can ignite and burn. Additionally, the distribution or orientation of the fuel can also impact combustion. The way the fuel is dispersed or arranged can affect the availability of oxygen for the combustion reaction, as well as the efficiency and speed of the combustion process.
8.
The three physical state of matter are solid, liquid and
Correct Answer
gas
Explanation
The three physical states of matter are solid, liquid, and gas. Solids have a definite shape and volume, while liquids have a definite volume but take the shape of their container. Gases, on the other hand, have neither a definite shape nor volume and can expand to fill the entire space available to them. They have particles that are far apart and move freely, resulting in their ability to flow and diffuse easily.
9.
What are the components of the fire tetrahedron?
Correct Answer
C. Heat, fuel, oxygen, self-sustained chemical chain reaction
Explanation
The components of the fire tetrahedron are heat, fuel, oxygen, and self-sustained chemical chain reaction. These components are necessary for a fire to occur. Heat provides the initial ignition source, fuel provides the material that can burn, oxygen is necessary for combustion, and the self-sustained chemical chain reaction allows the fire to continue burning. Without any one of these components, a fire cannot be sustained.
10.
Temperature at which a liquid releases sufficient vapors to ignite but not sustain combustion is called its:
Correct Answer
B. Flash point
Explanation
Flash point refers to the temperature at which a liquid releases enough vapors to ignite but not sustain combustion. It is an important safety measure as it indicates the potential fire hazard of a substance. A liquid with a lower flash point is considered more flammable, while a higher flash point indicates a lower risk of ignition. Therefore, flash point is the correct answer to the question.
11.
Liquids having a flash point that is greater 100 degrees F is called:
Correct Answer
B. Combustible liquid
Explanation
A liquid with a flash point greater than 100 degrees Fahrenheit is called a combustible liquid. This means that the liquid has a higher temperature at which it can release enough vapor to ignite, compared to a flammable liquid. Combustible liquids have a higher threshold for ignition, making them less prone to catching fire compared to flammable liquids.
12.
Liquids having a flash point that is less than 100 degrees F is called:
Correct Answer
A. Flammable liquid
Explanation
Liquids with a flash point below 100 degrees F are considered flammable because they can easily ignite and burn at normal temperatures. These liquids have a low ignition point and can produce flammable vapors, making them highly dangerous. Combustible liquids, on the other hand, have a higher flash point and are less likely to ignite at lower temperatures. Therefore, the correct answer is "Flammable liquid."
13.
In which state must fuel be for flaming combustion to occur
Correct Answer
A. Gaseous
Explanation
Flaming combustion occurs when fuel is in the gaseous state. In this state, the fuel molecules are able to mix and react with oxygen molecules in the air, creating a flame. In contrast, fuels in a solid or liquid state cannot easily mix with oxygen and therefore do not support flaming combustion. Fine divided fuels may burn, but they do not produce a visible flame. Heating and oxidizing the fuel can facilitate the conversion of the fuel into a gaseous state, enabling flaming combustion to occur.
14.
The chemical decomposition of a substance through the action of heat is called
Correct Answer
C. Pyrolysis
Explanation
Pyrolysis is the correct answer because it refers to the chemical decomposition of a substance through the action of heat. During pyrolysis, the substance is heated to high temperatures, causing it to break down into smaller molecules or elements. This process is commonly used in industries such as oil refining and waste management to convert organic materials into useful products like fuel or char. Reduction, oxidation, and chemical chain reaction are not appropriate answers because they do not specifically describe the decomposition of a substance through heat.