B, radon is correct. Interestingly, it often collects in basements from radioactive decay of rocks such as granite that contain uranium. Because it is an unreactive noble gas and because it is denser than air it sits in basements and must be pumped out. It collects in human lungs and is the second leading cause of lung cancer behind smoking.
Reactant are those that combine or reacts to give products !!
so in combustion of ethane ; ethane and o2 are reactants so ... your answer is B !!
Answer:
When you put sugar inside of a cup with water, the sugar is still visible because it's molecules have just gotten in touch with water molecules. The sugar molecules are still attracted to each other but as you stir it, it seems to disappear but not completely. When the water is stirred sugar mix with water and water molecules place themselves between the sugar ones.
Conclusion: It suggests that the sugar molecules are more attracted to water molecules which is why they easily separate from each other.