Mass is density times volume
0.760 x 531 = 403.56g
404g if 3 sig figs
Weeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee
Solar- the sun is not always shining, for example at night you can't get any energy from the sun
Wind-it's not always windy
Water- there can be drought
Really the main issue of all three of these is that they are not always available
