Tag: chemistry

Questions Related to chemistry

Each of the following statement is correct except

chemistry solid state imperfections in solids

  1. the lattice positions left vacant by anion and occupied by electrons are called F-centres

  2. the presence of F-centres makes the lattice electrically neutral and diamagnetic

  3. the presence of F-centres gives colour to the crystals

  4. F-centres contain unpaired electrons

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Correct Option: B

In feldspar and zeolite, $Si^{4+}$ ions are replaced by which ions?

chemistry solid state imperfections in solids

  1. Oxide ion

  2. Hydroxide ion

  3. Aluminium ion

  4. Potassium ion

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Correct Option: C
Explanation:

Generally, the ion exchange tendency of a material depends on the extent of isomorphous substitution in the tetrahedral framework. Thus, the $Si^{4+}$ ions of feldspar and zeolite are replaced by $Al^{3+}$ (aluminium ion).

ZnO shows yellow colour on Heating due to:

chemistry solid state imperfections in solids

  1. d-d transition

  2. C-T spectra

  3. Higher polarisation caused by $Zn^{2+}$ ion

  4. F-centres

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Correct Option: D
Explanation:

$ZnO$ shows yellow colour of heating due to F-centre

$ZnO\longrightarrow Zn^{2+}+2e^-+\cfrac{1}{2}O _2$
Electron get trapped in anion sites. This is called as F-centre. Due to F-centre colour of many compounds occurs.

Interstitial compounds are formed when small atoms are trapped inside the crystal lattice of
metals. Which of the following is not the characteristic property of interstitial compounds?

chemistry d and f block elements imperfections in solids solid solutions formation of complex compounds and constituent of catalysts general characteristics of first transition series

  1. They have high melting points in comparison to pure metals.

  2. They are very hard.

  3. They retain metallic conductivity.

  4. They are chemically very reactive.

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Correct Option: D
Explanation:
Interstitial compounds have high melting points in comparison to pure metals. They are very hard and retain metallic conductivity. They are chemically inert i.e. not reactive.

Which of the following is an interstital compound ?

chemistry d and f block elements imperfections in solids solid solutions formation of complex compounds and constituent of catalysts general characteristics of first transition series

  1. $ PdCI _2 $

  2. $ NH _3 $

  3. $ ZnO$

  4. $ TiH $

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Correct Option: A

Which of the following is incorrect about interstitial compounds?

chemistry d and f block elements imperfections in solids solid solutions formation of complex compounds and constituent of catalysts general characteristics of first transition series

  1. Very reactive

  2. High metallic conductivity

  3. Very hard

  4. High melting point

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Correct Option: A
Explanation:

Interstital compound are almost inert so (A) is wrong statement.

Which forms interstitial compounds?

chemistry d and f block elements imperfections in solids solid solutions formation of complex compounds and constituent of catalysts general characteristics of first transition series

  1. $Fe$

  2. $Co$

  3. $Ni$

  4. All

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Correct Option: D
Explanation:

A interstitial compound has ions or atoms of a nonmetal occupy interstitial positions in a metal lattice. All of the three transition metal mentioned above have the tendency to form interstitial compounds.

Which of the following is not soluble in $NaOH$?

chemistry d and f block elements imperfections in solids solid solutions formation of complex compounds and constituent of catalysts general characteristics of first transition series

  1. $Fe(OH) _3$

  2. $Zn(OH) _2$

  3. $Al(OH) _3$

  4. $Sn(OH) _2$

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Correct Option: A

Addition of non-metals like B and C to the interstitial sites of a transition metal results the metal :

chemistry d and f block elements imperfections in solids solid solutions formation of complex compounds and constituent of catalysts general characteristics of first transition series

  1. of more ductability

  2. of less ductability

  3. Less malleable

  4. of more hardness

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Correct Option: B,C,D
Explanation:

Addition of non-metals like B and C to the interstitial sites of a transition metal results in the  more hardness so it will be less ductile and less malleable.
Hence options B,C & D are correct.

Find the solid which has brilliant blue color.
chemistry the d-and f-block elements imperfections in solids solid solutions formation of complex compounds and constituent of catalysts general characteristics of first transition series

  1. $Fe _2O _3$

  2. $CuSO _4$

  3. $NaBr$

  4. $KCl$

  5. $Ca(OH) _2$

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Correct Option: B
Explanation:

Copper sulphate $\displaystyle CuSO _4$ has brilliant blue color.
$Cu(II)$ ions with an outer electronic configuration of  $\displaystyle 3d^{9}$ have one unpaired electron. This results in blue colour which is due to $d-d$ transitions.