How much energy does a 930 nm wave of light have? (The speed of light in a vacuum is 3.00 x 108 m/s, and Planck's constant is 6.626 x 10-34 Jos.)
A. 1.85 x 10-31 J
B. 4.68 x 1018 j
C. 2.14 x 10-19 J
D. 4.21 x 1035 J

What is the number of moles of chemical units represented by 9.03x10^24? and how do i show work? (dumb it down )

Answer asap need to be answered by wednesday morning explain how a buffer works, using an ethanoic acid / sodium ethanoate system including how the system resists changes in ph upon addition of a small amount of base and upon addition of a small amount of acid respectively. include the following calculations in your i. calculate the ph of a solution made by mixing 25cm3 0.1m ch3cooh and 40cm3 0.1m ch3coo-na+. [ka = 1.74 x 10-5 m] ii. calculate the ph following the addition of a 10cm3 portion of 0.08 m naoh to 500cm3 of this buffer solution. iii. calculate the ph following the addition of a 10cm3 portion of 0.08 m hcl to 200cm3 of the original buffer solution.

Select the correct lewis structure for fluorine which is group 7a element?