The substances which have very low ignition temperature and can easily catch fire when brought near a flame are called __________ substances.

Introduction / Context:
This question relates to basic concepts in combustion and fire safety. Understanding terms such as ignition temperature, combustible and inflammable is important in everyday life and in science. Substances that catch fire very easily pose greater risks and are often labelled with warning symbols. The question asks for the specific term used for substances that ignite readily because they have very low ignition temperature.

Given Data / Assumptions:

• We consider substances with very low ignition temperature.
• They can easily catch fire when brought near a flame.
• We are asked to identify the correct descriptive term.
• Options include hazardous, perilous, incombustible, inflammable and non reactive.

Concept / Approach:
Ignition temperature is the lowest temperature at which a substance catches fire and continues to burn. Substances with low ignition temperatures need only a small amount of heat or a small flame to start burning. In school chemistry, such substances are called inflammable or highly inflammable. The word hazardous simply means dangerous in a general sense and does not specifically refer to ease of catching fire. Perilous also means dangerous but is not a scientific term. Incombustible means cannot burn and is opposite to what is described. Non reactive refers to chemical inertness, not flammability.

Step-by-Step Solution:
Step 1: Note that the question emphasises very low ignition temperature and easy catching fire. Step 2: Recall that substances like petrol, alcohol and LPG are described as inflammable or highly inflammable, meaning they catch fire very easily. Step 3: Examine option D, inflammable. This is the standard term used on warning labels and in textbooks to mark materials that burn easily. Step 4: Option A, hazardous, is a general safety term that can apply to many types of risks, not only fire, and does not specifically describe ignition temperature. Step 5: Option B, perilous, is also a general English word for dangerous, not a technical classification. Step 6: Option C, incombustible, means not capable of burning, which is opposite to what is described in the question. Step 7: Option E, non reactive, indicates lack of chemical reactivity and does not specifically address how easily a material burns. Step 8: Thus the correct term is inflammable.

Verification / Alternative check:
You can verify this by thinking about labels on petrol pumps, gas cylinders and paint tins, which carry fire hazard symbols and often include the word inflammable or flammable. In many school science textbooks, examples of substances with low ignition temperature are given, and such materials are referred to as inflammable substances. This consistent usage in both daily life and textbooks confirms that inflammable is the intended term here.

Why Other Options Are Wrong:
Hazardous and perilous describe overall danger and do not specifically refer to how easily a material catches fire. Incombustible means fireproof or not capable of burning, which is directly contrary to the description of easily catching fire. Non reactive is a broad term for low chemical reactivity and may apply to inert gases, which do not burn easily at all. None of these capture the combination of low ignition temperature and easy flammability described in the question.

Common Pitfalls:
Some students may be confused by the prefix in in inflammable and think it means not flammable. Historically, inflammable and flammable both mean capable of catching fire, and many safety organisations now prefer the simpler term flammable to avoid confusion. In exam contexts, however, inflammable is still widely used to describe substances that ignite easily. Paying attention to definitions given in your textbook can help avoid misinterpretation of this word.

Final Answer:
Substances with very low ignition temperature that can easily catch fire are called inflammable substances.