Composition and size of the nucleus; isotopes, isobars and isotones — practice questions

Question 1 · difficulty L1 · recall

The atomic number Z equals the number of

• A. protons in the nucleus
• B. neutrons only
• C. nucleons minus electrons
• D. protons plus neutrons

Question 2 · difficulty L1 · understanding

The mass number A equals

• A. number of protons only
• B. number of protons plus neutrons
• C. number of neutrons only
• D. number of electrons plus protons in every ion

Question 3 · difficulty L2 · understanding

Isotopes are nuclei with

• A. same A but different Z
• B. same neutron number but different Z
• C. same Z but different A
• D. different Z and same electron count only

Question 4 · difficulty L2 · application

Isobars are nuclei with

• A. same Z and different A
• B. same neutron number only
• C. same binding energy necessarily
• D. same A but different Z

Question 5 · difficulty L3 · application

Isotones have

• A. the same neutron number
• B. the same proton number
• C. the same mass number only
• D. the same charge and mass always

Question 6 · difficulty L3 · application

Nuclear radius is approximately described by

• A. R=R0 A
• B. R=R0 A^(1/3)
• C. R=R0/A
• D. R=R0 A²

Question 7 · difficulty L4 · analysis

If mass number increases by a factor of 8, nuclear radius increases by a factor of

• A. 8
• B. 4
• C. 2
• D. sqrt(8)

Question 8 · difficulty L4 · analysis

Two isotopes of the same element necessarily have

• A. different proton numbers
• B. the same mass number
• C. different chemical identity by atomic number
• D. the same number of protons but different numbers of neutrons

Question 9 · difficulty L5 · analysis

Because R∝A^(1/3), nuclear volume is approximately proportional to

• A. A
• B. A^(1/3)
• C. A²
• D. 1/A

Question 10 · difficulty L5 · analysis

A nucleus has A=56 and Z=26. Its neutron number is

• A. 26
• B. 30
• C. 56
• D. 82