Isotopes — Homi Bhabha Exam Chemistry MCQs with Solutions
Free Homi Bhabha Exam Chemistry Isotopes MCQs with step-by-step solutions (5 questions). Part of Atoms, Molecules & Structure. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Isotopes · medium · theory
Isotopes of an element have the same number of ______ but a different number of ______:
A. electrons; protons
B. neutrons; protons
C. protons; neutrons ✓ Correct
D. protons; electrons
Solution: Isotopes have the same atomic number (protons) but different mass numbers (neutrons).
Q2 — Isotopes · medium · theory
Carbon-12 and Carbon-14 are isotopes because they have the same number of protons but different numbers of:
A. electrons
B. protons
C. molecules
D. neutrons ✓ Correct
Solution: Both have 6 protons; C-12 has 6 neutrons and C-14 has 8 neutrons.
Q3 — Isotopes · hard · theory
Isotopes of an element show ______ chemical properties because they have the same ______:
A. identical; number of electrons (electronic configuration) ✓ Correct
B. different; number of neutrons
C. identical; number of neutrons
D. different; atomic number
Solution: Chemical behaviour depends on electrons; isotopes have the same electron arrangement, so identical chemistry.
Q4 — Isotopes · hard · numerical
Two isotopes of an element have mass numbers 35 and 37 with atomic number 17. The numbers of neutrons in them are:
A. 18 and 20 ✓ Correct
B. 18 and 18
C. 35 and 37
D. 17 and 17
Solution: Neutrons $= A - Z$: $35 - 17 = 18$ and $37 - 17 = 20$.
Q5 — Isotopes · medium · theory
The isotope used for carbon dating of ancient fossils is:
A. Carbon-14 ✓ Correct
B. Cobalt-60
C. Carbon-12
D. Uranium-235
Solution: The radioactive isotope Carbon-14 is used to estimate the age of once-living materials.