Which half-reaction correctly describes an oxidation?
ca(s) + 2e" __ca2+ (aq)
br2 + 2e —_2br"
na+ (aq) —> na(s)+e
cr(s)—> cr3+ (aq) + 3e

If the mass of the products measured 120g what would the mass of the reactants a. 30g b. 60g c. 120g d. 240g

Tin has ten stable isotopes. the heaviest, 124sn, makes up 5.80% of naturally occuring tin atoms. how many atoms of 124sn are present in 82.0 g of naturally occurring tin? what is the total mass of the 124sn atoms in this sample?

Is 9 correct? and can someone me with 10? it’s due tomorrow, you