In recent years, scientists have discovered hundreds of planets orbiting other stars. some of these planets are in orbits that are similar to that of earth, which orbits the sun ( = 1.99 × 10³⁰ kg) at a distance of 1.50 × 10¹¹ m, called 1 astronomical unit (1 au). others have extreme orbits that are much different from anything in our solar system. the following problem relates to one of these planets that follows circular orbit around its star. assume the orbital period of earth is 365 days. part a hd 10180g orbits with a period of 600 days at a distance of 1.4 au from its star. what is the ratio of the star's mass to our sun's mass?

List four observations that indicate that a chemical reaction may be taking place

How would the number of moles (n) of o2 change if the atmospheric pressure doubled but all other variables stayed the same

Answer asap need 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.