(b) Mention the reaction involved.(c) Why is excessive use of CFCs a cause of concern?20. List three factors that could lead to speciation. Which of these cannot be amajor factor in the speciation of a self-pollinating plant species and why?321.A green stemmed rose plant denoted by GG and a brown stemmed roseplant denoted by gg are allowed to undergo a cross with each other.(a) List your observations regarding(1) Colour of stem in their F, progeny(ii) Percentage of brown stemmed plants in F, progeny if P. plantsare self pollinated.(ii) Ratio of GG and Gg in the F, progeny.(b) Based on the finding of this cross, what conclusion can be drawn?22(a)Water has refractive index 1.33 and alcohol has refractive index 1.36.Which of the two medium is optically denser ? Give reason for youranswer.(b)Draw a ray diagram to show the path of a ray of light passing based on the findings of this cross,what conclusion can be drawn?​