Why do you think that tropospheric NO2 concentrations have changed, based on the video Tale of 3 cities

Several billion years ago which gas was the least prevailant in the atmosphere

In guinea pigs, black fur (b) is dominant over white fur (b). cross a heterozygous (hybrid) black guinea pig with a homozygous (purebred) white guinea pig. complete a punnett square, identify the genotype(s), phenotype(s), and probability (% and fraction) that the offspring will be black and white?

Kendra has the ability to cover a distance in a short period of time. she is said to have a lot of agility power strength