NFPA 921 Exam (2024/2025) | Actual Questions and Answers Latest Updated 2024/2025 (Graded, Exams of Physical anthropology

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NFPA 921 Exam ( 2024 /2025) | Actual Questions and Answers Latest Updated

2024 /2025 (Graded A+)

3.2.1* Approved. Answer ✔✔Acceptable to the authority having jurisdiction. 3.2.2* Code. Answer ✔✔A standard that is an extensive compilation of provisions covering broad subject matter or that is suitable for adoption into law independently of other codes and standards. 3.2.3* Guide. Answer ✔✔A document that is advisory or informative in nature and that contains only non-mandatory provisions. A guide may contain mandatory statements such as when a guide can be used, but the document as a whole is not suitable for adoption into law. 3.2.4* Recommended Practice. Answer ✔✔A document that is similar in content and structure to a code or standard but that contains only non-mandatory provisions using the word "should" to indicate recommendations in the body of the text. 3.2.5* Standard. Answer ✔✔An NFPA Standard, the main text of which contains only mandatory provisions using the word "shall" to indicate requirements and that is in a form generally suitable for mandatory reference by another standard or code or for adoption into law. Non- mandatory provisions are not to be considered a part of the requirements of a standard and shall be located in an appendix, annex, footnote, informational note, or other means as permitted in the NFPA Manual of Style. When used in a generic sense, such as in the phrase "standards development process" or "standards development activities," the term "standards" includes all NFPA Standards, including Codes, Standards, Recommended Practices, and Guides. 3.3.1* Absolute Temperature. Answer ✔✔A temperature measured in Kelvins (K) or Rankines (R). 3.3.2 Accelerant. Answer ✔✔A fuel or oxidizer, often an ignitible liquid,

intentionally used to initiate a fire or increase the rate of growth or spread of fire. 3.3.3 Accident Answer ✔✔An unplanned event that interrupts an activity and sometimes causes injury or damage or a chance occurrence arising from unknown causes; an unexpected happening due to carelessness, ignorance, and the like. 3.3.4 Active Fire Protection System. Answer ✔✔A system that uses moving mechanical or electrical parts to achieve a fire protection goal. 3.3.5 Ambient. Answer ✔✔Someone's or something's surroundings, especially as they pertain to the local environment; for example, ambient air and ambient temperature. 3.3.6 Ampacity. Answer ✔✔The maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. [70, Article 100] 3.3.7 Ampere. Answer ✔✔The unit of electric current that is equivalent to a flow of one coulomb per second; one coulomb is defined as 6.24 × 1018 electrons. 3.3.8 Arc. Answer ✔✔A high-temperature luminous electric discharge across a gap or through a medium such as charred insulation. 3.3.9 Arc Mapping. Answer ✔✔The systematic evaluation of the electrical circuit configuration, spatial relationship of the circuit components, and identification of electrical arc sites to assist in the identification of the area of origin and analysis of the fire's spread. 3.3.10 Arc Site. Answer ✔✔The location on a conductor with localized damage that resulted from an electrical arc. 3.3.11 Arcing Through Char. Answer ✔✔Arcing associated with a matrix

of charred material (e.g., charred conductor insulation) that acts as a semi-conductive medium. 3.3.12 Area of Origin. Answer ✔✔A structure, part of a structure, or general geographic location within a fire scene, in which the "point of origin" of a fire or explosion is reasonably believed to be located. (See also 3.3.142, Point of Origin.) 3.3.13 Arrow Pattern. Answer ✔✔A fire pattern displayed on the cross section of a burned wooden structural member. 3.3.14 Arson. Answer ✔✔The crime of maliciously and intentionally, or recklessly, starting a fire or causing an explosion. 3.3.15 Auto ignition. Answer ✔✔Initiation of combustion by heat but without a spark or flame. 3.3.16 Autoignition Temperature. Answer ✔✔The lowest temperature at which a combustible material ignites in air without a spark orflame. 3.3.17 Backdraft. Answer ✔✔A deflagration resulting from the sudden introduction of air into a confined space containing oxygen deficient products of incomplete combustion. 3.3.18 Bead. Answer ✔✔A rounded globule of re-solidified metal at the end of the remains of an electrical conductor that was caused by arcing and is characterized by a sharp line of demarcation between the melted and unmelted conductor surfaces. 3.3.19 Blast Pressure Front. Answer ✔✔The expanding leading edge of an explosion reaction that separates a major difference in pressure between normal ambient pressure ahead of the front and potentially damaging high pressure at and behind the front.

3.3.20 BLEVE. Answer ✔✔Boiling liquid expanding vapor explosion. 3.3.21 Bonding. Answer ✔✔The permanent joining of metallic parts to form an electrically conductive path that ensures electrical continuity and the capacity to conduct safely any current likely to be imposed. 3.3.22 British Thermal Unit (Btu). Answer ✔✔The quantity of heat required to raise the temperature of one pound of water 1°F at the pressure of 1 atmosphere and temperature of 60°F; a British thermal unit is equal to 1055 joules, 1.055 kilojoules, and 252.15 calories. 3.3.23 Burning Rate. Answer ✔✔See 3.3.105, Heat Release Rate (HRR). 3.3.24* Calcination of Gypsum. Answer ✔✔A fire effect realized in gypsum products, including wallboard, as a result of exposure to heat that drives off free and chemically bound water. 3.3.25 Calorie. Answer ✔✔The amount of heat necessary to raise 1 gram of water 1°C at the pressure of 1 atmosphere and temperature of 15°C; a calorie is 4.184 joules, and there are 252.15 calories in a British thermal unit (Btu). 3.3.26 Cause. Answer ✔✔The circumstances, conditions, or agencies that brought about or resulted in the fire or explosion incident, damage to property resulting from the fire or explosion incident, or bodily injury or loss of life resulting from the fire or explosion incident. 3.3.27 Ceiling Jet. Answer ✔✔A relatively thin layer of flowing hot gases that develops under a horizontal surface (e.g., ceiling) as a result of plume impingement and the flowing gas being forced to move horizontally 3.3.28 Ceiling Layer. Answer ✔✔A buoyant layer of hot gases and smoke produced by a fire in a compartment.

3.3.29 Char. Answer ✔✔Carbonaceous material that has been burned or pyrolyzed and has a blackened appearance. 3.3.30 Char Blisters. Answer ✔✔Convex segments of carbonized material separated by cracks or crevasses that form on the surface of char, forming on materials such as wood as the result of pyrolysis or burning. 3.3.31 Clean Burn. Answer ✔✔A distinct and visible fire effect generally apparent on noncombustible surfaces after combustible layer(s) (such as soot, paint, and paper) have been burned away. The effect may also appear where soot has failed to be deposited because of high surface temperatures. 3.3.32* Combustible. Answer ✔✔Capable of undergoing combustion. 3.3.33* Combustible Gas Indicator. Answer ✔✔An instrument that samples air and indicates whether there are ignitible vapors or gases present. 3.3.35 Combustion. Answer ✔✔A chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light in the form of either a glow or flame. 3.3.36 Combustion Products. Answer ✔✔The heat, gases, volatilized liquids and solids, particulate matter, and ash generated by combustion. 3.3.37 Competent Ignition Source. Answer ✔✔An ignition source that has sufficient energy and is capable of transferring that energy to the fuel long enough to raise the fuel to its ignition temperature. 3.3.38 Conduction. Answer ✔✔Heat transfer to another body or within a body by direct contact. 3.3.39 Convection. Answer ✔✔Heat transfer by circulation within a medium such as a gas or a liquid.

3.3.40 Creep. Answer ✔✔The tendency of a material to move or deform permanently to relieve stresses. 3.3.41 Current. Answer ✔✔A flow of electric charge. 3.3.42 Deductive Reasoning. Answer ✔✔The process by which conclusions are drawn by logical inference from given premises. 3.3.43 Deflagration. Answer ✔✔Propagation of a combustion zone at a velocity that is less than the speed of sound in the unreacted medium. [68, 2013] 3.3.44 Density. Answer ✔✔The mass of a substance per unit volume, usually specified at standard temperature and pressure. The density of water is approximately one gram per cubic centimeter. The density of air is approximately 1.275 grams per cubic meter. 3.3.45 Detection. Answer ✔✔(1) Sensing the existence of a fire, especially by a detector from one or more products of the fire, such as smoke, heat, infrared radiation, and the like. (2) The act or process of discovering and locating a fire. 3.3.46 Detonation. Answer ✔✔Propagation of a combustion zone at a velocity greater than the speed of sound in the unreacted medium. [68, 2013 3.3.47 Diffuse Fuel. Answer ✔✔A gas, vapor, dust, particulate, aerosol, mist, fog, or hybrid mixture of these, suspended in the atmosphere, which is capable of being ignited and propagating a flame front. 3.3.48 Diffusion Flame. Answer ✔✔A flame in which fuel and air mix or diffuse together at the region of combustion.

3.3.49 Drop Down. Answer ✔✔The spread of fire by the dropping or falling of burning materials. Synonymous with "fall down." 3.3.50 Effective Fire Temperatures. Answer ✔✔Temperatures reached in fires that produce physical effects that can be related to specific temperature ranges. 3.3.51 Electric Spark. Answer ✔✔A small, incandescent particle created by some arcs. 3.3.52* Empirical Data. Answer ✔✔Factual data that is based on actual measurement, observation or direct sensory experience rather than on theory. 3.3.53 Energy. Answer ✔✔A property of matter manifested as an ability to perform work, either by moving an object against a force or by transferring heat. 3.3.54 Entrainment. Answer ✔✔The process of air or gases being drawn into a fire, plume, or jet. 3.3.55 Explosible. Answer ✔✔A material with a pressure ratio (maximum pressure/pressure at ignition, in absolute units) equal to or greater than 2.0 in any test when tested using the explosibility or Go/No-Go screening test described in Section 13 of ASTM E1226, Standard Test Method for Explosibility of Dust Clouds. 3.3.56 Explosion. Answer ✔✔The sudden conversion of potential energy (chemical or mechanical) into kinetic energy with the production and release of gases under pressure, or the release of gas under pressure. These high-pressure gases then do mechanical work such as moving, changing, or shattering nearby materials.

3.3.57 Explosion Dynamics. Answer ✔✔Study of how chemistry, physics, fire science, engineering disciplines of fluid and solid mechanics, and heat transfer interact to influence explosion behavior. 3.3.58 Explosive. Answer ✔✔Any chemical compound, mixture, or device that functions by explosion. 3.3.59 Explosive Material. Answer ✔✔Any material that can act as fuel for an explosion. 3.3.60 Exposed Surface. Answer ✔✔The side of a structural assembly or object that is directly exposed to the fire. 3.3.61 Extinguish. Answer ✔✔To cause to cease burning. 3.3.62 Failure. Answer ✔✔Distortion, breakage, deterioration, or other fault in an item, component, system, assembly, or structure that results in unsatisfactory performance of the function for which it was designed. 3.3.63 Failure Analysis. Answer ✔✔A logical, systematic examination of an item, component, assembly, or structure and its place and function within a system, conducted in order to identify and analyze the probability, causes, and consequences of potential and real failures. 3.3.64 Fall Down. Answer ✔✔See 3.3.49, Drop Down. 3.3.65 Finish Rating. Answer ✔✔The time in minutes, determined under specific laboratory conditions, at which the stud or joist in contact with the exposed protective membrane in a protected combustible assembly reaches an average temperature rise of 121°C (250°F) or an individual temperature rise of 163°C (325°F) as measured behind the protective membrane nearest the fire on the plane of the wood. 3.3.66 Fire. Answer ✔✔A rapid oxidation process, which is a chemical

reaction resulting in the evolution of light and heat in varying intensities. 3.3.67 Fire Analysis. Answer ✔✔The process of determining the origin, cause, development, responsibility, and, when required, a failure analysis of a fire or explosion. 3.3.68 Fire Area. Answer ✔✔The boundary of fire effects within a scene in which the area of origin will be located. The fire area is characterized by identifying the border between damaged and undamaged areas, which are distinguishable by fire effects and patterns created by flame, heat, and smoke. 3.3.69 Fire Cause. Answer ✔✔The circumstances, conditions, or agencies that bring together a fuel, ignition source, and oxidizer (such as air or oxygen) resulting in a fire or a combustion explosion. 3.3.70* Fire Dynamics. Answer ✔✔The detailed study of how chemistry, fire science, and the engineering disciplines of fluid mechanics and heat transfer interact to influence fire behavior. 3.3.71 Fire Effects. Answer ✔✔The observable or measurable changes in or on a material as a result of a fire. 3.3.72 Fire Hazard. Answer ✔✔Any situation, process, material, or condition that can cause a fire or explosion or that can provide a ready fuel supply to augment the spread or intensity of a fire or explosion, all of which pose a threat to life or property. 3.3.73 Fire Investigation. Answer ✔✔The process of determining the origin, cause, and development of a fire or explosion. 3.3.74 Fire Patterns. Answer ✔✔The visible or measurable physical

changes, or identifiable shapes, formed by a fire effect or group of fire effects. 3.3.75 Fire Propagation. Answer ✔✔See 3.3.78, Fire Spread. 3 .3.76 Fire Scene Reconstruction. Answer ✔✔The process of recreating the physical scene during fire scene analysis investigation or through the removal of debris and the placement of contents or structural elements in their pre-fire positions. 3.3.77* Fire Science. Answer ✔✔The body of knowledge concerning the study of fire and related subjects (such as combustion, flame, products of combustion, heat release, heat transfer, fire and explosion chemistry, fire and explosion dynamics, thermodynamics, kinetics, fluid mechanics, fire safety) and their interaction with people, structures, and the environment. 3.3.78 Fire Spread. Answer ✔✔The movement of fire from one place to another. 3.3.79 First Fuel Ignited. Answer ✔✔The first fuel ignited is that which first sustains combustion beyond the ignition source. 3.3.80 Flame. Answer ✔✔A body or stream of gaseous material involved in the combustion process and emitting radiant energy at specific wavelength bands determined by the combustion chemistry of the fuel. In most cases, some portion of the emitted radiant energy is visible to the human eye. [72, 2013] 3.3.81 Flame Front. Answer ✔✔The flaming leading edge of a propagating combustion reaction zone. 3.3.82 Flameover. Answer ✔✔The condition where unburned fuel (pyrolysate) from the originating fire has accumulated in the ceiling layer to a sufficient concentration (i.e., at or above the lower flammable limit) that it ignites and burns; can occur without ignition of, or prior to, the ignition of other fuels separate from the origin

3.3.83 Flammable. Answer ✔✔Capable of burning with a flame. 3.3.84 Flammable Limit Answer ✔✔The upper or lower concentration limit at a specified temperature and pressure of a flammable gas or a vapor of an ignitible liquid and air, expressed as a percentage of fuel by volume that can be ignited 3.3.85 Flammable Liquid. Answer ✔✔A liquid that has a closed-cup flash point that is below 37.8°C (100°F) and a maximum vapor pressure of 2068 mm Hg (40 psia) at 37.8°C (100°F). (See also 3.3.34, Combustible Liquid.) 3.3.86 Flammable Range. Answer ✔✔The range of concentrations between the lower and upper flammable limits. [68, 2013] 3.3.87 Flash Fire. Answer ✔✔A fire that spreads by means of a flame front rapidly through a diffuse fuel, such as dust, gas, or the vapors of an ignitible liquid, without the production of damaging pressure. 3.3.88 Flash Point of a Liquid Answer ✔✔The lowest temperature of a liquid, as determined by specific laboratory tests, at which the liquid gives off vapors at a sufficient rate to support a momentary flame across its surface. 3.3.89 Flashover. Answer ✔✔A transition phase in the development of a compartment fire in which surfaces exposed to thermal radiation reach ignition temperature more or less simultaneously and fire spreads rapidly throughout the space, resulting in full room involvement or total involvement of the compartment or enclosed space 3.3.90 Forensic (Forensic Science). Answer ✔✔The application of science to answer questions of interest to the legal system 3.3.91 Fuel. Answer ✔✔A material that will maintain combustion under specified environmental conditions. [53, 2011

3.3.92 Fuel Gas. Answer ✔✔Natural gas, manufactured gas, LP-Gas, and similar gases commonly used for commercial or residential purposes such as heating, cooling, or cooking. 3.3.93 Fuel Load. Answer ✔✔The total quantity of combustible contents of a building, space, or fire area, including interior finish and trim, expressed in heat units or the equivalent weight in wood 3.3.94 Fuel-Controlled Fire. Answer ✔✔A fire in which the heat release rate and growth rate are controlled by the characteristics of the fuel, such as quantity and geometry, and in which adequate air for combustion is available 3.3.95 * Full Room Involvement Answer ✔✔Condition in a compartment fire in which the entire volume is involved in combustion of varying intensities. 3.3.96 Gas. Answer ✔✔The physical state of a substance that has no shape or volume of its own and will expand to take the shape and volume of the container or enclosure it occupies. 3.3.97 Glowing Combustion. Answer ✔✔Luminous burning of solid material without a visible flame. 3.3.98 Ground. Answer ✔✔A conducting connection, whether intentional or accidental, between an electrical circuit or equipment and earth or to some conducting body that serves in place of the earth 3.3.99 Ground Fault. Answer ✔✔An unintended current that flows outside the normal circuit path, such as (a) through the equipment grounding conductor; (b) through conductive material in contact with lower potential (such as earth), other than the electrical system ground (metal water or plumbing pipes, etc.); or (c) through a combination of these ground return paths. 3.3.100 Hazard. Answer ✔✔Any arrangement of materials that presents the potential for harm 3.3.101 * Heat. Answer ✔✔A form of energy characterized by vibration of molecules and capable of initiating and supporting chemical changes and changes of state.

3.3.102 Heat and Flame Vector. Answer ✔✔An arrow used in a fire scene drawing to show the direction of heat, smoke, or flame flow. 3.3.103 Heat Flux. Answer ✔✔The measure of the rate of heat transfer to a surface or an area, typically expressed in kW/m2, or W/cm 3.3.104 * Heat of Ignition. Answer ✔✔The heat energy that brings about ignition. 3.3.105 * Heat Release Rate (HRR). Answer ✔✔The rate at which heat energy is generated by burning. 3.3.106 Heat Transfer. Answer ✔✔The exchange of thermal energy between materials through conduction, convection, and/or radiation. 3.3.107 High Explosive. Answer ✔✔A material that is capable of sustaining a reaction front that moves through the unreacted material at a speed equal to or greater than that of sound in that medium [typically 1000 m/sec (3000 ft/sec)]; a material capable of sustaining a detonation. (See also 3.3.46, Detonation.) 3.3.108 High-Order Damage. Answer ✔✔A rapid pressure rise or high-force explosion characterized by a shattering effect on the confining structure or container and long missile distances. 3.3.109 * Hybrid Mixture. Answer ✔✔An explosible heterogeneous mixture, comprising gas with suspended solid or liquid particulates, in which the total flammable gas concentration is ≥10 percent of the lower flammable limit (LFL) and the total suspended particulate concentration is ≥10 percent of the minimum explosible concentration (MEC). [68, 2013] 3.3.110 Hypergolic Material. Answer ✔✔Any substance that will spontaneously ignite or explode upon exposure to an oxidizer. 3.3.111 Ignitible Liquid. Answer ✔✔Any liquid or the liquid phase of any material that is capable of fueling a fire, including a flammable liquid, combustible liquid, or any other material that can be liquefied and burned.

3.3.112 Ignition. Answer ✔✔The process of initiating self-sustained combustion. 3.3.113 Ignition Energy. Answer ✔✔The quantity of heat energy that should be absorbed by a substance to ignite and burn. 3.3.114 * Ignition Temperature. Answer ✔✔Minimum temperature a substance should attain in order to ignite under specific test conditions.