Which Science Elective is easier class to take between biology, chemistry, environmental science, integrated science and doesn't required a lab?

The answer
to the question of which class is easier will depend on the school and level.  You can look at
your schools course catalog and see how many units the class is worth, and if a lab is
required.  Talk to your advisor about this.  Most schools include general education introductory
classes that help non-science majors meet the science requirement without difficult
coursework.

Of your options, integrated science is more likely to be a lower
level class.  This is often a survey class, involving a sampling of different scientific
fields.  Biology, chemistry, and physics all require labs and are content-heavy.  Environmental
science is also popular with non-science majors, as is geology (at my school they jokingly
called the class rocks for jocks).  Most schools also have classes for teachers, which might
be more interesting if you are planning to be a teacher.

Talk to friends and
your advisor, and perhaps sit in on a session or two of one of the classes.  Your school might
also have a syllabus online for the classes.  Check your registrar or school web
site.

href="https://catalog.csun.edu/general-education/">https://catalog.csun.edu/general-education/