Which of the following is true of group 6a?

includes chlorine

includes sulfur

gain 2 electrons

tend to form +2 ions

have 5 valence electrons

The answer to your question is: Includes sulfur and gain two electrons

Explanation:

Includes Chlorine  This option is wrong, Chlorine belongs to group VII.

Includes Sulfur  This option is true, Group VI includes Oxygen, Sulfur, Selenium, Tellurium.

Gain 2 electrons . This option is true, Elements in group VI have six valence electrons so they gain to electrons to become estable.

Tend to form +2 ions  This option is wrong, this elements form -2 ions

Have 5 valence electrons This option is wrong, this elements have 6 valence electrons.

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.