Lets take x gm of Hg and x gm of I2 present in the initial mixture
Hg + I2 → HgI2
2Hg + I2 → Hg2I2
Actually mercuric iodide (HgI2) cant be made by reacting iodine with mercury. Pure Mercurous iodide actually forms when we add mercury to iodine . So the ratio is 1 : 0