Which is not a characteristic of white phosphorous? (a) It has a low melting point \(\left(44^{\circ} \mathrm{C}\right)\). (b) It is soluble in nonpolar solvent such as carbon disulphide \(\left(\mathrm{CS}_{2}\right)\) (c) At temperatures less than \(0^{\circ} \mathrm{C}\) it is converted to red phosphorous (d) It bursts into flames when exposed to air, thus it is stored under water.

Phosphorus, a versatile non-metal, manifests itself in several different forms, known as allotropes. These allotropes possess distinct physical and chemical properties, making phosphorus an element of great interest in chemistry. The most common allotropes of phosphorus are white, red, and black phosphorus.

Understanding the chemical properties of white phosphorus is crucial for grasping its reactivity and uses. White phosphorus is notorious for its reactivity with air. It ignites spontaneously at room temperature when exposed to oxygen, exhibiting a characteristic garlic-like odor. This property necessitates its storage underwater or in an inert atmosphere to prevent accidental combustion.

Additionally, white phosphorus has a low melting point of approximately 44°C and is soluble in non-polar solvents like carbon disulfide (CS₂). This solubility contrasts with the other allotropes of phosphorus, which are generally insoluble in CS₂. White phosphorus can also be converted into other allotropes, such as red phosphorus, through a controlled heating process or exposure to sunlight, rather than just lowering the temperature as the question in the exercise might imply.

Preparing for competitive exams like the National Eligibility cum Entrance Test (NEET) in India requires a deep understanding of chemistry, including the properties and allotropes of elements like phosphorus. To effectively grasp these concepts, students should:

• Review and memorize the physical and chemical properties of elements, including their allotropes.
• Practice application-based questions that involve the recognition and prediction of chemical behavior.
• Employ visual aids, such as diagrams and charts, to better understand the structural differences between allotropes.
• Conduct experiments, if possible, under guided supervision to observe the properties of substances like white phosphorus firsthand.

Tackling problems systematically by understanding the fundamental concepts and then applying them to solve exercises can lead to a comprehensive preparation strategy for the chemistry section of NEET.