Tag: chemistry

Questions Related to chemistry

Heavy water is called so because:

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

  1. it has dissolved salts in it

  2. it is an oxide of heavy hydrogen

  3. it is a hydride of heavy oxygen

  4. all of the above

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Correct Option: B
Explanation:

Heavy water is called so because, it is the oxide of heavy hydrogen $(D _2$ or $ _1H^2)$.

Which of the following is not a deuterolysis reaction

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

  1. $SO _{3}+D _{2}O\rightarrow D _2SO _{4}$

  2. $CaC _{2}+2D _{2}O\rightarrow Ca(OD) _{2}+C _{2}D _{2}$

  3. $Mg _{3}N _{2}+6D _{2}O\rightarrow 3Mg(OD) _{2}+2ND _{3}$

  4. $AlCl _{3}3D _{2}O\rightarrow Al(OD) _{3}+3DCl$

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Correct Option: A
Explanation:

Option $A$ is not a deuterolysis reaction. It is not a chemical reaction at all. 

Deuterolysis reactions are reactions in which a salt reacts with heavy water to give a base and an acid.

Which of the following statement regarding $D _{2}O$ is correct?

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

  1. It is an isotope of hydrogen

  2. It is used as a bleaching agent

  3. It is used as a moderator in atomic reactors

  4. It is used as a coolant in atomic reactors

Show answer
Correct Option: C,D
Explanation:

$D _2O$  is used as a moderator in atomic reactors and as coolant in atomic reactors.

The chain reaction in a reactor is sustained by the free neutrons coming from one fission being absorbed by a Uranium nucleus, which then fissions itself. The probability of this absorbtion is increased if the neutrons are moving slowly. The purpose of the moderator is to slow the neutrons down. 
Lighter nuclei make better moderators than heavy nuclei. If a neutron were to hit an infinitely heavy nucleus, it would bounce off in a different direction with the same velocity. When a neutron hits a nucleus of atomic mass one head on, it comes to a complete stop. 
So, we want to use light nucleus. The reason water $(H _2O)$ is unsuitable is that it is likely to absorb the neutrons instead of slowing them down. The probability of water absorbing a neutron is more than $200$ times higher than the probability of deuterium (which already has a neutron) doing so.
Hence, options C and D are correct.

The products formed when heavy water is reacted with magnesium nitride, is/are _______.

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

  1. $NH _{3}Mg\left ( OH \right ) _{2}$

  2. $NH _{3}Mg\left ( OD \right ) _{2}$

  3. $ND _{3}Mg\left ( OH \right ) _{2}$

  4. $ND _{3}Mg\left ( OD \right ) _{2}$

Show answer
Correct Option: D
Explanation:

$Mg _{ 3 }{ N } _{ 2 }+6{ D } _{ 2 }O \rightarrow 2{ ND } _{ 3 }+ 3Mg(OD) _{ 2 }$

$NaOH + D _{2}O \rightarrow NaOD + HDO$, is a:

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

  1. exchange reaction.

  2. deuterolysis reaction.

  3. hydrolysis reaction.

  4. softening reaction.

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Correct Option: A
Explanation:
$NaOH + D _2O \rightarrow NaOD + HDO$, is exchange reaction where hydrogen in $NaOH$ is replaced by $D$ in $D _2O$ became $NaOD$.

Heavy water is used as a:

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

  1. fuel in engines

  2. semiconductor

  3. moderator in nuclear reactors

  4. insulator in steam engines

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Correct Option: C
Explanation:

Answer:-

Heavy water is used in certain types of 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.

Heavy water is used as _______ in nuclear reactor.

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

  1. controller

  2. moderator

  3. promoter

  4. none of these

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Correct Option: B
Explanation:

Heavy water acts as a neutron moderator in nuclear reactors to slow down neutrons so that they are more likely to react with the fissile $U _{235}$ than with $U _{238}$, which captures neutrons without fission process.

Heavy hydrogen has __  neutron and  _ proton in the nucleus.

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

  1. 2 and 1

  2. 1 and 2

  3. 1 and 1

  4. 2 and 2

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Correct Option: C
Explanation:
Deuterium is called as a heavy hydrogen.
Heavy hydrogen $\left( _{ 1 }^{ 2 }{ D } \right) $ $=$ $1$ neutron
                                            $1$ proton
                                            ${ 1e }^{ - }$

The reactions of heavy water are slow. The reason is :

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

  1. heavy water is associated.

  2. heavy water is dissociated.

  3. heavy water is of higher mass.

  4. heavy water is of lower mass.

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Correct Option: C
Explanation:

As Deuterium contains one extra neutron, so heavy water has higher molecular mass than water and because of that it is less reactive.

A molecule of heavy water has two deuterium atoms in place of the two protium atoms of ordinary "light" water. The weight of a heavy water molecule, however, is not substantially different from that of a normal water molecule,

Deuteromethane can be prepared if $D _{2}O$ reacts with:

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

  1. $Al _{4}C _{3}$

  2. $CaC _{2}$

  3. both A and B

  4. none of the above

Show answer
Correct Option: A
Explanation:
On hydrolysis of $Al _{4}C _{3}$ methane forms, similarly $D _2O$ reacts with $Al _{4}C _{3}$ and deuteromethane forms as the product.