Chromium is manufactured by heating a mixture of chromium(III) oxide with aluminium powder. Cr2O3(s) + 2Al(s) → 2Cr(s) + Al2O3(s)

a=Calculate the mass of aluminium needed to react with 50 g of Cr2O3.
b=Calculate the mass of chromium produced from 50 g of Cr2O3.
c=Calculate the mass of chromium produced from 5 kg of Cr2O3.
d=Calculate the mass of chromium produced from5 tonnes of Cr2O3.

Note: 1 tonne = 1,000,000 g
Ar: Cr = 52, O = 16, Al = 27

Plz choose one of the compounds from the table and explain how you know the numbers of atoms in your formula. is it possible for two different compounds to be made from the exact same two elements? why or why not? with a limited number of elements (less than 120 are known), does this mean we also have a small number of compounds or do we have a large number of compounds in this world?

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.

At element makes up all organic compounds?