Which element contains the same number of energy levels as oxygen?

Why does a red shoe appear red in daylight

Adeuteron, 21h, is the nucleus of a hydrogen isotope and consists of one proton and one neutron. the plasma of deuterons in a nuclear fusion reactor must be heated to about 3.02×108 k . what is the rms speed of the deuterons? express your answer using two significant figures.

Measurements that have similar values are: a. usually accurate b. sometimes accurate c. always accurate d. never accurate