A scientist mixed two samples together: a colorless liquid that melts at 12°C and a
yellow solid that melts at 390°С. She
analyzed the results and found two ending
substances. One of the ending substances
was a gray solid. This ending substance is
made up of the repeating group of atoms
shown above. Which of the diagrams to the
left shows the repeating groups of atoms
that make up the samples the scientist
mixed together?

Describe the interaction that occurs between two objects with the same electrical charge.

Suppose a pair of chemical compounds a and b can react in two different ways: a + b -> c reaction 1 gives product c. a + b -> d reaction 2 gives product d. the following facts are known about the two reactions: . reaction 1 is endothermic and reaction 2 is exothermic. if a reaction vessel is charged (filled) with a and b , then at first d is produced faster than c. use these facts to sketch a qualitative reaction energy diagram for both reactions. note: because these sketches are only qualitative, the energies don? t have to be exact. they only have to have the right relationship to each other. for example, if one energy is less than another, that fact should be clear in your sketch.

Asolution of naoh has a concentration of 25.00% by mass. what mass of naoh is present in 0.250 g of this solution? use the periodic table in the toolbar if needed. 0.0625 g what mass of naoh must be added to the solution to increase the concentration to 30.00% by mass? g