Einstein's famous equation, E = mc^2 relates the mass (m) of an object to energy (E). The speed of light (c), is the constant of proportionality. Einstein formulated the equation within his theory of special relativity. Indeed, a physical interpretation of this equation is that any given mass is equivalent to the energy given by the equation, if it were suddenly converted to energy. Therefore the answer to the question is true.
Yes the kingdom is more specific
A mixture is said to be homogeneous if its composition is uniform throughout the mixture. They are referred to as solutions. On the other hand, heterogeneous mixture does not have uniform composition. The substances present in the mixture have visible difference or phases.
Sea water is composed of salt, sand and water. Here, salt and water form homogeneous mixture but due to the presence of sand, the mixture is heterogeneous. Salt dissolves in water and the solution has uniform composition but sand does not dissolve in water, even after vigorous mixing, after some time it settles at the bottom resulting formation of layers. Thus, sea water containing salt, water and sand is a heterogeneous mixture.