C. 4 N is the answer if not then i be dumb!!!
The best type of electromagnetic wave to use to warm food that is safe would be the infrared wave. The correct answer is B.
Energy is the capacity to do work. Energy exists in various forms in the entire universe.
It may be light,sound,electric,magnetic,kinetic,potential,thermal energy etc.
As per the law of conservation of energy, it is neither created not destroyed. It can change from one form to another form.The total energy of the universe is always constant.
The process in which energy will change from one form to another form is called energy conversion.
There is also another terminology for energy conversion called energy transformation.
Energy transference is the process in which energy will be transferred from one body to another body.
Hence the correct answer to this question will be conversion and transformation
A leaf is organic matter because organic matter refers to anything from something living. because a leaf is living or was at one point it is organic matter
A beat is an interference pattern between two sounds of slightly different frequencies, perceived as a periodic variation in volume whose rate is the difference of the two frequencies. Frequency beat is equal to,

The reference frequency in our case would be 392Hz, and since there is the possibility of the upper and lower range for the amount of beats per second that the two possible frequencies are heard would be


Therefore the two possible frequencies the piano wire is vibrating at, would be 396Hz and 388Hz