If I did this correctly the balanced equation would be:
14H⁺+Cr₂O₇²⁻+6I⁻→3I₂+2Cr³⁺+7H₂O
oxidation half: (iodide was oxidized)
2I⁻→I₂+2e⁻
reduction half: (chromium was reduced)
14H⁺+Cr₂O₇²⁻+6e⁻→2Cr³⁺+7H₂O
H⁺ comes from the solution. It is in the final reaction since in redox reactions the oxygen is turned into water since it can't just go away. I multiplied the oxidation half reaction by 3 in order for both half reactions to half the same number of electrons since equal numbers of electrons need to be lost and gained for the reaction to be balanced.
I hope this helps. Let me know if anything is unclear.
I am pretty sure that the answer is B. extrusive rock. I hope that this helps you!! Good Luck!!
Number of moles is defined as the ratio of given mass in g to the molar mass.
The mathematical formula is:
Number of moles =
(1)
Number of zinc atoms is equal to
, by Avogadro number, number of moles can be calculated.
As, 1 mol=
atoms, hence,

= 0.2822 mol
Now, from formula (1), calculate mass in g (molar mass of zinc = 65.4 g/mol)
0.2822 mol =
mass in g = 
= 18.45588 g
Thus, by rounding off the above number, it will come near about 19 g approximately.
Hence, option (C) is the correct answer.