Which element would react most like calcium (Ca)?
O A. O
O B. Mg
O C. C
D. Ti

It is a mixture. simply put, a compound must be pure, that is, of only one chemical structure and composition. a mixture is made of different chemical substances (i.e. elements, molecules, compounds) that are not chemically bonded to each other, but instead physically grouped together, as in the case of gasoline (a homogeneous solution).

Answer (b) supersaturation;

They make up examples of physical properties 

Qand k are only the same when the forward rate of the reaction has reached zero.