Decomposition of NI3 produces nitrogen gas and iodine. How many grams of the reactant would be required to react completely to give 7.97g of the iodine.

Grams of the reactant would be required is 8.26 g

Explanation:

Decomposition of NI3 is :

2 NI3 (s) > N2 (g) + 3 I2 (g)

2 mol1 mol3 mol

2 x 394.7 g/mol28 g/mol3 x 253.8 g/mol

789.4 g28 g761.4 g

From chemical equation it is cleared that

761.4 g of iodine is obtained from = 789.4 g of NI3

Therefore,

7.97 g of iodine is obtained from = 789.4 g x 7.97 g / 761.4 of NI3

                                                       = 6291.518 / 761.4 of NI3

                                                       =  8.26 g  of NI3

Hence

Grams of the reactant would be required = 8.26 g

the answer is true.

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)