Heavy water is so called because it
[amp_mcq option1=”contains a number of salts as in sea water” option2=”is the mercury contaminated water” option3=”is saline water used in hospitals” option4=”contains the heavier isotope of hydrogen in water” correct=”option4″]
This question was previously asked in
UPSC CAPF – 2011
The correct option is D. Heavy water, chemically represented as D₂O, contains deuterium, which is an isotope of hydrogen. Unlike the common hydrogen atom (protium, ¹H) which has only a proton, deuterium (²H or D) has a proton and a neutron, making it approximately twice as heavy as protium. Therefore, water molecules formed with deuterium (heavy water) are heavier than those formed with protium (ordinary water, H₂O).
The question asks for the reason why heavy water is called “heavy”. It relates to its chemical composition and the presence of a heavier isotope of hydrogen.