Q.Give the uses of heavy water.
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Heavy water, D2O, is the deuterium analogue of ordinary water and is chemically very similar to H2O, since it undergoes essentially the same types of reactions (bent structure, hydrogen bonding through O–D, amphoteric behaviour) governed by the same electron configuration of oxygen. However, its physical properties differ noticeably because deuterium is roughly twice as massive as protium: D2O has a higher boiling point (about 101.4∘C versus 100∘C), a higher melting point, greater density, and greater viscosity than ordinary water. It is manufactured by the prolonged electrolysis of ordinary water, because the lighter H2O molecules are preferentially decomposed at the electrodes, leaving the residual water progressively enriched in D2O. Despite its chemical similarity to ordinary water, D2O is not considered suitable for regular dri …
Heavy water is used as a nuclear moderator, a nuclear coolant, and a tracer for reaction/metabolic mechanisms. …
Step 1. As a moderator in nuclear reactors -- heavy water slows down the fast neutrons released by fission to the thermal energies needed to sustain the chain reaction.
Step 2. As a coolant in nuclear reactors -- heavy water absorbs and carries away the heat generated inside the reactor core. …
List heavy water's three stated applications from Section 4.6.2: …
- Omitting the tracer use and giving only the two nuclear-reactor roles -- th …
- CBSE 2025Set ANNUAL1 markMCQQ.The formula of heavy water is(a) H2(18)O(b) H2(16)O(c) H2O2(d) D2O
›Reveal solutionSolution
Heavy water has the formula D2O.
Heavy water is chemically identical to ordinary water except that its hydrogen atoms are replaced by deuterium (2H, symbol D), the heavier stable isotope of hydrogen (mass number 2, containing 1 proton and 1 neutron). Its formula is therefore D2O, di …
- CBSE 2023Set ANNUAL1 markMCQQ.The boiling point of heavy water [D2O] is ________.(a) 375.4 K(b) 373.4 K(c) 376.2 K(d) 374.4 K
›Reveal solutionSolution
D2O (heavy water) boils at about 101.4 degree C = 374.4 K, a little higher than ordinary water's 100 degree C = 373 K.
Heavy water, D2O, is chemically similar to ordinary water H2O but has deuterium (2H) in place of ordinary hydrogen (1H). Because deuterium is twice as massive as protium, the O-D bond is slightly stronger and shorter than the O-H bond, and hydrogen bonding between D2O molecules is marginally stronger. This raises D2O's boiling point slightly above that of ordinary water: D2O boils at about 101.4 degree C ( …
- CBSE 2023Set ANNUAL1 markMCQQ.Heavy water is(a) H_2O(b) D_2O(c) N_2O(d) CO
›Reveal solutionSolution
Heavy water is D2O.
Heavy water is water in which both ordinary hydrogen (protium, 1H) atoms are replaced by deuterium (2H or D), the heavier stable isotope of hydrogen. Its formula is D2O. It has a slightly higher density, boiling point and freezing point than ordinary water and is used as a neutron …
- CBSE 2022Set ANNUAL1 markMCQQ.Which is used as a moderator in a nuclear reactor?(a) Cd(b) V-235(c) Pb(d) D2O
›Reveal solutionSolution
Heavy water (D2O) is used as a moderator in nuclear reactors because deuterium nuclei slow down fast neutrons by elastic collision while absorbing very few of them.
In a nuclear fission reactor, fast neutrons released by fission must be slowed to 'thermal' speeds so they can efficiently trigger further fission in fuel like U-235. A moderator does this by elastic collisions with light nuclei. D2O (heavy water) is an effective moderator because deuterium (mass close to a neutron) slows neutrons efficiently while having a very low neutron-capture cross-section. (Note: the paper's own option (b) prints 'V-235', which looks like a typesetting slip for the reactor fuel …
- CBSE 2022Set ANNUAL1 markMCQQ.Match the following: Use of heavy water(a) Orientation(b) Fluorine(c) Lavoisier(d) Strong reducer(e) Bute-2-ene(f) Acetone(g) In atomic reactor
›Reveal solutionSolution
'Use of heavy water' matches with 'In atomic reactor', since D2O (heavy water, made from the hydrogen isotope deuterium) is used as a neutron moderator in nuclear reactors.
Heavy water, D2O, is made using deuterium (2H), an isotope of hydrogen with one extra neutron. Because deuterium nuclei slow down fast neutrons efficiently through elastic collisions while absorbing very few of them, D2O is used as a …
- CBSE 2019Set ANNUAL1 markMCQQ.Which is hard water? [Note: the Hindi text of this question actually asks ‘भारी जल किसे कहते हैं?’ (What is called heavy water?) — the printed English translation says ‘hard water’ instead of ‘heavy water’, a real translation inconsistency in the official paper itself; both language versions are transcribed faithfully.](a) H2O2(b) H2O(c) D2O(d) D2O2
›Reveal solutionSolution
Heavy water is D₂O — water in which the hydrogen atoms are replaced by the heavier hydrogen isotope deuterium (D).
Ordinary water is H₂O. Deuterium (²₁H, symbol D) is an isotope of hydrogen with one proton and one neutron, roughly twice the mass of protium (¹₁H). Water formed from deuterium and oxygen, D₂O, is therefore called 'heavy water' — it has a higher density and higher boiling point than ordinary water an …
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