Ethene (C2H4) can be halogenated by the following reaction:
C2H4(g)+X2(g)⇌C2H4X2(g)
where X2 can be Cl2 (green), Br2 (brown), or I2 (purple). Examine the three figures below representing equilibrium concentrations in this reaction at the same temperature for the three different halogens. Rank the equilibrium constants for these three reactions from largest to smallest.
Rank from largest to smallest. To rank items as equivalent, overlap them.

these nuts

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.