Atomic number, mass number and isotopes

Question 1

Carbon has atomic number 6. How many neutrons are in the isotope carbon-12?

Answer 

Question 2

An atom of aluminium (aluminum) is written ²⁷₁₃Al (mass number 27, atomic number 13). How many protons does it have?

Answer 

Question 3

A sodium atom loses one electron to become a sodium ion. What is its charge?

• A. 0
• B. −1
• C. +1
• D. +11

Question 4

Hydrogen has atomic number 1. How many neutrons are in the isotope hydrogen-1?

Answer 

Question 5

An atom of chlorine is written ³⁵₁₇Cl (mass number 35, atomic number 17). How many electrons does it have?

Answer 

Question 6

An atom has 11 protons, 12 neutrons and 11 electrons. What is its mass number?

• A. 23
• B. 11
• C. 34
• D. 12

Question 7

Carbon has atomic number 6. How many neutrons are in the isotope carbon-12?

Answer 

Question 8

An atom of silicon is written ²⁸₁₄Si (mass number 28, atomic number 14). How many protons does it have?

Answer 

Question 9

An atom has 11 protons, 12 neutrons and 11 electrons. What is its mass number?

• A. 23
• B. 12
• C. 11
• D. 34

Question 10

Uranium has atomic number 92. How many neutrons are in the isotope uranium-238?

Answer 

Question 11

An atom of calcium is written ⁴⁰₂₀Ca (mass number 40, atomic number 20). How many electrons does it have?

Answer 

Question 12

A sodium atom loses one electron to become a sodium ion. What is its charge?

• A. 0
• B. +1
• C. +11
• D. −1

Question 13

Chlorine has atomic number 17. How many neutrons are in the isotope chlorine-35?

Answer 

Question 14

An atom of oxygen is written ¹⁶₈O (mass number 16, atomic number 8). How many protons does it have?

Answer 

Question 15

Which number is the same for all isotopes of an element?

• A. the number of neutrons
• B. the atomic number
• C. the relative mass
• D. the mass number

Question 16

Chlorine has atomic number 17. How many neutrons are in the isotope chlorine-37?

Answer