In 1913, Niels Bohr used photo emission spectra, like the one shown, to propose a new model for the dun. 656 nm
434 nm
ורוח 410
486 nm
What feature of the atom did the spectra lead Bohr to include in his model?
А.
Electrons are negatively charged.
В.
An atom is a fundamental piece of matter.
C.
Electrons occupy specific energy levels.
D. O Atoms contain a central nucleus.

Agroup of students is studying convection currents. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other in an area with warm air. after 10 minutes, the balloons are released from a height of 1 meter. which of the following do the students most likely observe? a. the balloons both rise. the cold balloon is larger than the warm balloon. b. the balloons rise at the same rate. both balloons are the same size. c. the warm balloon expands and rises. the cold balloon shrinks and sinks. d. the cold balloon expands and rises. the warm balloon shrinks and sinks.

Drag each label to the correct location on the chart. classify each reaction as endothermic or exothermic.

If 1.8 l of water is added to 2.5l of a 7.0 molarity koh solution, what is the molarity of the new solution