Question

the number of known isotope is roughly
a) 100
b) 1000
c) 2500
d) 5000
e) more than 3100​

Answer 1

The number of known isotopes is roughly (a) 100.

• Isotopes are atoms that have the same atomic number but different mass numbers.
• They have the same number of protons and electrons. so, they have identical chemical properties but differ in their physical properties such as boiling point, melting point and density.
• For example, isotopes of carbon are ¹²C, ¹³C and ¹⁴C, all have the same atomic number which is 6. similarly, isotopes of hydrogen are hydrogen, deuterium, and tritium having mass numbers equal to 1,2 and 3 respectively. all the isotopes of hydrogen have the same atomic number 1 but the mass number is different.
• Isotopes of oxygen are 16O, 17O, and 18O.

Answer 2

The number of known isotope is roughly (a) 100