Which of the following materials can potentially cause explosions if present as dust in the air?

The correct answer is that coal, wood, and zirconium powder can all potentially cause explosions if present as dust in the air. This phenomenon is known as a dust deflagration, which occurs when combustible dust particles become suspended in the air and are ignited.

Wood dust and coal dust are known for their explosive potential because they can readily ignite and create a rapid combustion reaction when in the right concentration and particle size. Similarly, zirconium powder is recognized for its high reactivity and ability to form an explosive mixture when airborne.

The key factor that results in dust deflagration is the mixture of fine particles that can be inhaled and come into contact with an ignition source, leading to a rapid, violent release of energy. Each of these materials displays the characteristics necessary for this kind of explosive hazard.

Understanding this aspect of hazardous materials is essential for ensuring workplace safety, particularly in industries where these types of dust may be produced, handled, or stored. It highlights the importance of proper ventilation, dust control measures, and training to avoid dust accumulation and mitigate explosion risks.