Answer:
Never smoke near a place where hydrogen is generated or being used. Remove all possible sources of flame and sparks. Hydrogen should only be generated and used in a well ventilated out door area. Precautions must be taken to remove all possibilities of fire or explosion.
A less intense wave will have fewer OSCILLATING AMPLITUDE than a more intense wave.
The intensity of a wave is the power transferred per unit area, where the area is measured on the plane perpendicular to the direction of propagation of the energy. Intense sounds are characterized by the particles of the medium vibrating back and forth with large amplitude.<span />
A range of values is given for the density of gasoline and corn syrup could be because these substances changes their volumes along with the changes in temperature which will result to a change in density as well. Hope this answers the question.