Q: Which is true statement about \${ D }_{ 2 }O\$ and \${ H }_{ 2 }O\$?

The dielectric constant of \$H_2O\: (78.39)\$ is higher than the dielectric constant of \$D_2O\: (78.06)\$. This is due to the lower molar mass of \$H_2O\$ as compared to that of \$D_2O\$. Due to this, \$NaCl\$ (and other ionic compounds) dissolve more in \$H_2O\$ than in \$D_2O\$.

Q: The number of protons, electrons and neutrons respectively in a molecule of heavy water is:

The formula for heavy water is \$D_2O\$.Deuterium contains \$1\$ proton, \$1\$ neutron and \$1\$ electron.Oxygen contains \$8\$ protons, \$8\$ neutrons and \$8\$ electrons.Hence, \$D_2O\$ contains \$2\ D\$ and \$1\ O\$ atoms.\$D_2\$ has \$2\$ protons, \$2\$ neutrons and \$2\$ electrons while \$O\$ has \$8\$ protons, \$8\$ neutrons and \$8\$ electrons. Hence, \$D_2 O\$ contains \$10\$ protons, \$10\$ electrons and \$10\$ neutrons.

Q: Hard water when passed through ion exchange resin containing \$RCOOH\$ group, becomes free from :

Hard water contains \$Ca\$ and \$Mg\$ salt so when it is passed through negative ion exchange resin, it capture cations from water and make it free from \$Ca^{+2}\$.

Q: \$D_{2}O\$ will have maximum density at :

Heavy water \$(D_2O)\$ will have maximum density at \$11.5^\circ C\$.It is about \$11\%\$ heavier than ordinary water.The density of heavy water at \$298\:K\$ is \$1.1059\$ g/ml.

Question 1

Which is true statement about ${ D }_{ 2 }O$ and ${ H }_{ 2 }O$?

Accepted Answer

The dielectric constant of $H_2O\: (78.39)$ is higher than the dielectric constant of $D_2O\: (78.06)$. This is due to the lower molar mass of $H_2O$ as compared to that of $D_2O$. Due to this, $NaCl$ (and other ionic compounds) dissolve more in $H_2O$ than in $D_2O$.

Question 2

Which one among the following is used as a moderator in nuclear reactors?

Accepted Answer

A moderator is a material used in a nuclear reactor to slow down the neutrons produced from fission. By slowing the neutrons down the probability of a neutron interacting with Uranium-235 nuclei is greatly increased thereby maintaining the chain reaction. Heavy water $(D_2O)$ is used as a moderator in nuclear reactor. It containing significantly more than the natural proportions (one in 6,500) of heavy hydrogen (deuterium, D) atoms to ordinary hydrogen atoms. Heavy water is used as a moderator in some reactors because it slows down neutrons effectively and also has a low probability of absorption of neutrons.

Question 3

When heavy water reacts with calcium carbide, the product formed is:

Accepted Answer

When heavy water reacts with calcium carbide, the products formed are deutero acetylene $(C_2 D_2)$ and calcium deuteroxide $(Ca(OD)_2)$.The reaction is as follows:$CaC_2 + 2 D_2O\rightarrow C_2D_2 + Ca(OD)_2$Hence, option D is the correct answer.

Question 4

The number of protons, electrons and neutrons respectively in a molecule of heavy water is:

Accepted Answer

The formula for heavy water is $D_2O$.Deuterium contains $1$ proton, $1$ neutron and $1$ electron.Oxygen contains $8$ protons, $8$ neutrons and $8$ electrons.Hence, $D_2O$ contains $2\ D$ and $1\ O$ atoms.$D_2$ has $2$ protons, $2$ neutrons and $2$ electrons while $O$ has $8$ protons, $8$ neutrons and $8$ electrons. Hence, $D_2 O$ contains $10$ protons, $10$ electrons and $10$ neutrons.

Question 5

Which compound is formed when calcium carbide reacts with heavy water?

Accepted Answer

When calcium carbide reacts with heavy water, deuterated acetylene ($C_{2}D_{2}$) is formed.$CaC_{2} + 2D_{2}O \rightarrow C_{2}D_{2} + Ca(OD)_{2}$

Question 6

Hard water when passed through ion exchange resin containing $RCOOH$ group, becomes free from :

Accepted Answer

Hard water contains $Ca$ and $Mg$ salt so when it is passed through negative ion exchange resin, it capture cations from water and make it free from $Ca^{+2}$.

Question 7

The physical constants which are less for $D_{2}O$ than $H_{2}O$ are:

Accepted Answer

Value of solvating ability and dielectric constant are less for ${ D }_{ 2 }O$ than ${ H }_{ 2 }O$ due to the strong $H$-bonding in ${ H }_{ 2 }O$ and the self ionization power of ${ H }_{ 2 }O$.

Question 8

Give uses of heavy water.

Accepted Answer

Uses of heavy water:1. Heavy water is used as neutron moderator in nuclear reactors.2. Heavy water is used in Neuclear Magnetic Resonance(NMR) spectroscopy. It is used for aqueous solutions involving the study of hydrogen nuclide.3. Heavy water is used in Fourier Transform Infrared(FTIR) Spectroscopy of proteins.4. Heavy water is used for metabolic rate testing in physiology and biology.5. Heavy water is used in formation of another hydrogen isotope called tritium.

Question 9

Observe the following statements:1. Heavy water is harmful to the growth of animals.2. Heavy water reacts with $\displaystyle { Al }_{ 4 }{ C }_{ 3 }$ and forms deuterated acetylene.3. $\displaystyle Ba{ Cl }_{ 2 }.2{ D }_{ 2 }O$ is an example of interstitial deuterate.The correct statements are:

Accepted Answer

The correct statements are 1 and 31. Heavy water is harmful for the growth of animals. It is slightly injurious to some of the living organisms.2. Heavy water reacts with  $\displaystyle { Al }_{ 4 }{ Cl }_{ 3 }$ and forms deuterated methane $\displaystyle { Al }_{ 4 }{ Cl }_{ 3 } +12D_2O \rightarrow 3CD_4 + 4Al(OD)_3$3. $\displaystyle Ba{ Cl }_{ 2 }.2{ D }_{ 2 }O$ is an example of interstitial deuterate.

Question 10

$D_{2}O$ will have maximum density at :

Accepted Answer

Heavy water $(D_2O)$ will have maximum density at $11.5^\circ C$.It is about $11\%$ heavier than ordinary water.The density of heavy water at $298\:K$ is $1.1059$ g/ml.

Properties and Uses of Heavy Water

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Heavy Water - Preparation, Properties and Uses

Heavy water

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