< var > CnH2n < /var ><var>CnH2n</var>
< var > Mr =14*2=28 < /var ><var>Mr=14∗2=28</var>
< var > 12n+2n=28 , 14n=28 , n=2 < /var ><var>12n+2n=28,14n=28,n=2</var>
< var > C2H4 < /var ><var>C2H4</var>
< var > CnH2n < /var ><var>CnH2n</var>
< var > Mr =14*2=28 < /var ><var>Mr=14∗2=28</var>
< var > 12n+2n=28 , 14n=28 , n=2 < /var ><var>12n+2n=28,14n=28,n=2</var>
< var > C2H4 < /var ><var>C2H4</var>