An electron in a hydrogen atom relaxes to the n = 3 level, emitting light with a wavelength of 1281nm. What is the value of n for the level in which the electron originated? En = -2.18×10-18/n2 J Or you may use the following equation: Ephoton = 2.18×10-18 (1/n12 – 1/n22) J,  (n1 < n2)   Mark your answer next to words "Final answer is". You must follow significant figure rules.   You must show your work here to receive any credit (you may receive 0 points for only showing your final answer).

An unknown element has two naturally occurring isotopes with masses 18.00 amu (A) and 21.00 amu (B) and has an atomic mass of 18.90 amu.  What’s the natural abundance of isotope A (%)?  Mark your answer next to words “Final answer is”. You must follow significant figure rules.   You must show your work here to receive any credit (you may receive 0 points for only showing your final answer).

The eyes of certain reptiles pass a single visual signal to the brain when the visual receptors are struck by photons of a wavelength of 849 nm. 1) What’s the energy of a single photon? 2) If a total energy of 3.15×10–14 J is required to trip the signal, what is the minimum number of photons that must strike the receptor? Mark your answer next to words “Final answer is”. You must follow significant figure rules.   You must show your work here to receive any credit (you may receive 0 points for only showing your final answer).

Choose the ground state electron configuration for Co3+.    

What is the charge of the ion most commonly formed by S?      

How do you target heterozygotes in a breeding program?

What allows artificial selection to succeed at selecting against a recessive allele?

What is selection in the context of animal breeding?

A greater probability of detection can be achieved with progeny and recessive gene frequency in the test mates.

What does natural selection primarily act on?