An effective cover letter:
a. makes an excellent first impression.
b. is well written and attractive.
c. convinces the reader to read the resume.
d. highlights the writerâs key qualifications.
e. emphasizes how the writerâs qualifications meet the employerâs needs. f. âall of the above

Carbon monoxide is usually more dangerous indoors.

Ifound the exercise on the internet. attached is the list mentioned above.in order for a compound to be considered optically active it can't have any axis or plan of symmetry. the molecule  shouldn't also  be superimposable on its mirror image.with such considerations, the compounds that are optically active are: -third compound on the first image is optically active; -second and third compound from the second image are optically actives.