Which of the following is not a physical property commonly used by scientist to classify stars

Give the set of reactants (including an alkyl halide and a nucleophile) that could be used to synthesize the following ether: draw the molecules on the canvas by choosing buttons from the tools (for bonds and charges), atoms, and templates toolbars, including charges where needed. ch3ch2och2ch2chch3 | ch3

Which factor is likely to impact the possible number of compounds ?

Is this correct if not can u correct me