In this paper, we estimate the temperature dependence of line intensities contributing to the observed features. As chlorine and potassium belongs to the group of poorly abundant elements with their respective photospheric abundances relative to H below 10^-6 in the solar plasma, their emissivity has not yet been directly calculated. Therefore, we present here the results of isoelectronic sequence interpolations of the intensity vs. temperature dependence for the strong lines corresponding to 1s^2 1S₀ - 1s2p ¹P₁ ("w" line) transition in He-like ions. Results of the calculations will be useful for the final identification of the lines observed and for determination of the absolute abundance of chlorine and potassium in solar corona.