Model in which electrons are found in fixed levels around the nucleus and require energy to move from level to level:
a. bohr model
c. quantum mechanical model
b. rutherford model
d. free-electron model

Iam in desperate need of with this !

Sugar is dissolved in water. which is the solute? sugar neither both water

Which of these statements best explains why space exploration should be encouraged? it prepares humans to live without oxygen. it dispel myths about objects in space. it prevents comets and asteroids from striking earth. it creates technology to absorb harmful radiations in space.