How can something with different atoms be a pure substance and not a mixture

What volume of a 2.00 m stock solution of naoh is needed to prepare 150. ml of 0.40 m solution?

Which of these sequences lists the correct order for the creation of sedimentary rock from sediment? a. deposition, burial, compaction, cementation b. burial, deposition, compaction, cementation c. compaction, deposition, burial, cementation d. cementation, deposition, burial, compaction

Melting and boiling are endothermic processes. this means that these processes absorb energy from their surroundings in order to occur. use this information and the data you collected in the phase change gizmo to describe what happens to the temperature of water when you boil it, then explain why this result occurs.