Question

The major product (X) formed when ethane-1, 2-diol is heated with excess of hydrogen iodide is
A.2-iodoethanol
B.1,2-diiodoethane
C.Iodoethane
D.ethene

Answer 1

Hint: The chemical formula for ethane-1,2-diol is $${\left(C{H}_{2}OH\right)}_2$$. Ethane-1,2-diol is also called Ethylene glycol, the simplest member of the glycol family of organic compounds.
We know that $$HI$$ is a source of $$H^{+}$$then ethane-1,2-diol react with$$HI$$(excess) we get $$C{H}_{2}I-C{H}_{2}I$$ since $$2I$$ on adjacent carbon are unstable under heating. So, if we lose $$2I$$ we get the result.

Complete answer: Chemical reaction when ethane-1, 2-diol is heated with excess of hydrogen iodide is
$${\left(C{H}_{2}OH\right)}_2+\underset{excess}{2HI}\stackrel{\mathrm{\Delta }}{\to }C{H}_2=C{H}_2+I_2$$
In this reaction a major product is $$C{H}_2=C{H}_2$$.
Where $$C_2{H}_4$$or $$C{H}_2=C{H}_2$$ is a chemical formula for ethylene. Ethylene is the most produced compound in organic chemistry. Ethylene is also called Ethene. It is the simplest Alkene, is an organic compound containing a $$C=C$$ double bond.
Hence, the correct option is (D).

Note:
Note that Ethylene is an unsaturated hydrocarbon (also called olefin). Ethane-1,2-diol is also known as Ethylene glycol. It is an organic compound. It is mainly used for two purposes, as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an odourless, colourless, sweet-tasting, viscous liquid. Also note that, a glycol is an alcohol with two hydroxyl groups on adjacent carbon atoms (a 1,2-diol). The common name ethylene glycol literally means “the glycol derived from ethylene.