Which of the following statements about biofuels is true? a. biofuels are composed of 100% renewable materials. b. algae is the leading source of biofuels. c. energy processing from corn biofuels is not energy efficient. d. corn is the only source of biofuels.

Phase changes are chemical changes. true or false

Aheavy piece of hanging sculpture is suspended by a90-cm-long, 5.0 g steel wire. when the wind blows hard, the wire hums at its fundamental frequency of 80hz. what is the mass of the sculpture?

Point charges q1=+2.00μc and q2=−2.00μc are placed at adjacent corners of a square for which the length of each side is 1.50 cm . point a is at the center of the square, and point b is at the empty corner closest to q2. take the electric potential to be zero at a distance far from both charges. part a what is the electric potential at point a due to q1 and q2? express your answer with the appropriate units.