Which element of Group 17 has two isotopes of masses 35 and 37 amu with average abundance of 75.77% and 24.23%, respectively? 

The correct answer is Chlorine.

Key Points

• Chlorine is the element of Group 17 that has two isotopes of masses 35 and 37 amu.
• The average abundance of the isotopes is 75.77% for 35 amu and 24.23% for 37 amu.
• Chlorine has the atomic number 17 and its chemical symbol is Cl.
• Chlorine is a pungent, green-yellow gas at room temperature and makes up about 0.0018% of the Earth's crust.
• It's widely known for its use in disinfecting drinking water as well as in bleach and other cleaning products

Additional Information

• Iodine:
  • Iodine is another member of Group 17, the Halogens. It has one stable isotope: Iodine-127.
  • It is a shiny, dark-grey to purple-black nonmetal that can be seen when it is at room temperature.
  • Iodine is essential for the production of thyroid hormones in the human body, with deficiency leading to goitre, an enlargement of the thyroid gland.
  • Its radioisotope, iodine-131, is used in medical treatment, particularly for thyroid conditions.
• Fluorine:
  • Fluorine is the lightest member of the halogens and has only one stable isotope: Fluorine-19.
  • It is a pale, yellow-green gas at room temperature and is the most reactive and electronegative of all elements.
  • The majority of fluorine is used in the manufacture of a variety of compounds, including an important class called fluorocarbons, that have many industrial applications.
• Astatine:
  • Astatine is a halogen and the heaviest element in Group 17. It is a radioactive element, and all its isotopes are short-lived; the most stable isotope, Astatine-210, has a half-life of 8.1 hours.
  • It is the rarest naturally occurring element and is typically produced synthetically.
  • Not much is known about astatine due to its scarcity, but it's believed to be a heavy, volatile, and highly reactive metalloid similar to the other halogens.