Tag: chemistry

Quizzes (490) Questions (9892)

Questions Related to chemistry

Multiple choice chemistry solid state imperfections in solids

Each of the following statement is correct except

  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
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

F-centres contain unpaired electrons, which makes the crystal paramagnetic, not diamagnetic. The other statements are correct descriptions of F-centres.

Multiple choice chemistry solid state imperfections in solids

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

  1. Oxide ion

  2. Hydroxide ion

  3. Aluminium ion

  4. Potassium ion
Reveal answer Fill a bubble to check yourself
C Correct answer
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).

Multiple choice chemistry solid state imperfections in solids

ZnO shows yellow colour on Heating due to:

  1. d-d transition

  2. C-T spectra
  3. Higher polarisation caused by $Zn^{2+}$ ion

  4. F-centres
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

Multiple choice 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

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?

  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.
Reveal answer Fill a bubble to check yourself
D Correct answer
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.
Multiple choice 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

Which forms interstitial compounds?

  1. $Fe$
  2. $Co$
  3. $Ni$

  4. All
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

Multiple choice 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

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

  1. $Fe(OH) _3$
  2. $Zn(OH) _2$
  3. $Al(OH) _3$
  4. $Sn(OH) _2$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Fe(OH)3 is a basic hydroxide and does not dissolve in NaOH. Zn(OH)2, Al(OH)3, and Sn(OH)2 are amphoteric and dissolve in strong bases like NaOH to form soluble complexes.

Multiple choice 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

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

  1. of more ductability

  2. of less ductability

  3. Less malleable

  4. of more hardness
Reveal answer Fill a bubble to check yourself
B,C,D Correct answer
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.

Multiple choice 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
Find the solid which has brilliant blue color.
  1. $Fe _2O _3$
  2. $CuSO _4$
  3. $NaBr$
  4. $KCl$
  5. $Ca(OH) _2$
Reveal answer Fill a bubble to check yourself
B Correct answer
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.