Practice free →
HomeCBSE Class 9chemistryatomicstructure › The element Fluorine has 9 protons and 10 neutro…

The element Fluorine has 9 protons and 10 neutrons. The mass number and atomic number are respectively:

AMass = 10, Atomic = 9
BMass = 9, Atomic = 10
CMass = 9, Atomic = 19
DMass = 19, Atomic = 9
Answer & Solution
Correct answer: D. Mass = 19, Atomic = 9
Atomic number Z = number of protons = 9. Mass number A = protons + neutrons = 9 + 10 = 19. So fluorine-19 (¹⁹F) is the common isotope. It is also the most reactive non-metal — needing just 1 electron to complete its octet (configuration 2, 7).
Solve this in the app — CBSE Class 9 practice & 24k+ MCQs →
Related questions