Again with the chemistry questions all help is appreciated :’)

How does the atmosphere to make earth livable? check all that apply. causes the seasons contains oxygen provides warmth creates important nutrients blocks harmful energy from the sun plz like !

Phosphoric acid is a triprotic acid ( =6.9×10−3 , =6.2×10−8 , and =4.8×10−13 ). to find the ph of a buffer composed of h2po−4(aq) and hpo2−4(aq) , which p value should be used in the henderson–hasselbalch equation? p k a1 = 2.16 p k a2 = 7.21 p k a3 = 12.32 calculate the ph of a buffer solution obtained by dissolving 18.0 18.0 g of kh2po4(s) kh 2 po 4 ( s ) and 33.0 33.0 g of na2hpo4(s) na 2 hpo 4 ( s ) in water and then diluting to 1.00 l.

Read "who built the pyramids? ”. leave this link open while you answer the questions throughout the assignment. give at least two reasons why some people claim the pyramids of giza were constructed by aliens.