Tag: hydrogen and its compounds

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Questions Related to hydrogen and its compounds

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

Compare the bond energy (B.E) of $O-H$ in water and $O-D$ in heavy water:

  1. B.E of $O-H >$ B.E of $O-D$
  2. B.E of $O-H <$ B.E of $O-D$
  3. B.E of $O-H =$ B.E of $O-D$
  4. B.E of $O-H =$ 2 times B.E of $O-D$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Boiling point of heavy water is more than normal water and therefore, bond energy of $O-H$ bond in water is lesser than bond energy of $O-D$ bond in heavy water. 


Also, bond length of $O-H$ is greater than $O-D$ and bond energy is inversely proportional to bond energy.

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

Heavy water is obtained by ?

  1. boiling water
  2. heatiing $H _{2}O _{2}$
  3. Prolonged electrolysis of $H _{2}O$

  4. All of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$D _{2}O$ is prepared by repeated electrolysis of ordinary water which contains a small amount of alkali. Ordinary water contains a very very small fraction (about 1 part in 6000 parts) of heavy water.

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

Atomic nuclear reactors use heavy water. This is different from ordinary water only to the extent that in place of hydrogen it contains:

  1. deuterium, a heavier isotope of hydrogen

  2. nitrogen, which is also a light element

  3. tritium, an heavier isotope of hydrogen

  4. a radioactive element
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Heavy water $(D _2O)$ is a compound containing deuterium and oxygen. It is used in the atomic nuclear reactor as a moderator. It differs from ordinary water $(H _2O)$ only because it has Deuterium i.e. a heavy isotope of hydrogen.

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.