Earth orbits once around the sun about every 365 days. the moon orbits around earth. about how many days does it take the moon to orbit twice around the sun?

a. 730
b. 365.
c. 64.
d.29

Astudent creates a model of a closed ecosystem by filling a glass tank half full with water, then adding 10 snails and two small aquatic plants. the next day, all the snails are dead. what is the most likely cause of their death?

Hydrogen atoms are excited by a laser to the =4n=4 state and then allowed to emit. what is the maximum number of distinct emission spectral lines (lines of different wavelengths) that can be observed from this system? 8 6 2 7 4 5 1 3 calculate the wavelength of the 4⟶14⟶1 transition. =λ=

Glass has a hardness that is in the middle of the hardness scale. what is the hardness of glass?