Answer: a. two substances present; two phases present : Heterogeneous mixture
b. two substances present; one phase present
: Homogeneous mixture
c. one substance present; one phase present
: pure substance.
d. one substance present; two phases present: Heterogeneous mixture
Explanation:
A pure substance is a substance which contains definite composition of only one type of component. Hence, it cannot be separated by physical means.
Mixture is a substance which contains two or more than two types of components and they can be separated by physical means as well.
Homogeneous mixtures: It is a mixture that has uniform composition throughout the solution and the particle size or shapes are not different. There is no physical boundary between the dispersed phase and dispersion medium.
Heterogeneous mixtures: It is a mixture that has non-uniform composition throughout the solution and the particle size or shapes are also different. There is a physical boundary between the dispersed phase and dispersion medium.
If there is solution with nonvolatile solute (<span>substance that does not readily </span>evaporate<span> into a </span>gas) <span>only the pure vapor of the solvent is present above the solution and solute stays in solution and do not enters vapor above solution. This is because nonvolatile solute has slow rate of evaporation and low vapore pressure.
If solution has two volatile components, composition of the vapor depends on vapor pressures of the components according </span><span>Raoult's Law.</span>
1 Kj ------------- 1000 J
?? --------------- 10 J
10 x 1 / 1000 => 0.01 Kj
D. Dependent on an objects position
-2 cuz 20 negative minus 18 positive is -2
