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

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 5

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 6

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 7

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 8

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.

Question 9

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 10

Heavy water  (D_{2}O)  freezes at ?

Accepted Answer

The freezing point of heavy water is  3.8^{0}C   or  276.8 K . The boiling point is  101.4^{0}C   or  374.4 K .

Properties and Uses of Heavy Water

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