I need heLp ASAP

Area of reduced temperature. - Visible from Earth. - Large amount of magnetic activity. Which part of the sun is best described by the characteristics listed above?

A)corona

B)sunspots

C)photosphere

D)solar flares

What is the composition, in atom percent, of an alloy that consists of 4.5 wt% pb and 95.5 wt% sn? the atomic weights for pb and sn are 207.19 g/mol and 118.71 g/mol, respectively.(a) 2.6 at% pb and 97.4 at% sn(b) 7.6 at% pb and 92.4 at% sn(c)97.4 at% pb and 2.6 at% sn(d) 92.4 at% pb and 7.6 at% sn

How many moles of air are there in a human lung with a volume of 2.4 l at stp? explain your answer

Compare and contrast the bohr model and the electron cloud models of the atom.