Pure substance element I think
Answer:
a. Molarity= 
b. Molality= 
Explanation:
Hello,
In this case, given the information about the aniline, whose molar mass is 93g/mol, one could assume the volume of the solution is just 200 mL (0.200 L) as no volume change is observed when mixing, therefore, the molarity results:

Moreover, the molality:

Best regards.
Answer:
The reflection of sound waves
Explanation:
An echo is a reflection of sound that bounces of of one thing to another.
Answer:
1 and 3
Explanation:
The vertical columns (groups) of the periodic table are arranged such that all its elements have the same number of valence electrons. All elements within a certain group thus share similar properties.
Answer:
C
Explanation:
If you add enough heat to a solid it eventually becomes a liquid