Tag: study of heavy water

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Multiple choice chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

If a mole of hydrogen molecule is heated to a high temoerature then which of the following reactions take place?

  1. $H _2{(g)} + 436 kJ mol^{-1} \rightarrow H{(g)} + H{(g)}$
  2. $2H2{(g)} + 820 kJ mol^{-1} \rightarrow 2H _2{(g)}$
  3. $H _2{(g)} + H _2{(g)} + 436kJ mol^{-1} \rightarrow H^{+} _{(aq)} + H^{-} _{(aq)}$
  4. $H _2{(g)} + 200kJ mol^{-1} \rightarrow H _{(g)} + H _{(g)}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The amount of energy required to break $H-H$ bond of 1 mole of gaseous hydrogen is 436 $kJ \ mol^{-1}$. This is known as bond dissociation enthalpy.
$H _2{(g)} + 436 \  kJ mol^{-1} \rightarrow  H{(g)} + H{(g)}$

Multiple choice chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

Some of the major uses of heavy water are given below. Which one is not correct?

  1. It is used as a moderator in nuclear.

  2. It is used as a tracer compound for studying reaction mechanism

  3. High concentration of heavy water accelerates the growth of plants

  4. It is used in preparing deuterium
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

High concentration of heavy water retards the growth of the plants. Tobacco seeds do not grow in heavy water.

Multiple choice chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

$D _2O$ can be obtained by:

  1. repeated distillation

  2. exchange process

  3. neutron emitting radioactive decay in presence of water

  4. exhaustive electrolysis of alkaline water
Reveal answer Fill a bubble to check yourself
A,B,D Correct answer
Explanation

Heavy water is deuterium oxide $(D _2O)$. Ordinary water contains a fraction (1 in 6000 parts) of heavy water. On large scale, it is produced by repeated electrolysis of ordinary water containing alkali. It is also produced by repeated distillation and condensation. It is also obtained by exchange process.

Multiple choice chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

Heavy water is used as a:

  1. fuel in engines

  2. semiconductor

  3. moderator in nuclear reactors

  4. insulator in steam engines
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Heavy metals is used as a moderator in nuclear reactors to bring the fission reaction by slowing down the neutrons and capturing them. The main reason is that the heavy water captures less neutrons than the normal water. Later it can be used as a fuel which has not undergone enrichment to increase the percentage of Uranium-235

Multiple choice chemistry hydrogen and its compounds heavy water study of heavy water hard water and soft water

$D _{2}O$ is used more in:

  1. chemical industry

  2. nuclear moderator

  3. pharmaceutical preparation

  4. insecticide preparations
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Heavy water is used in nuclear reactors, where it acts as a neutron moderator to slow down neutrons so that they are more likely to react with the fissile uranium-235 than with uranium-238, which captures neutrons without fissioning.