Chemistry

Chemical Bonding and Molecular Structure

1,420 Questions

This section tests your knowledge of chemical bonding, molecular structure, and hybridization. It covers ionic and covalent bonds, octet rule exceptions, and molecular geometry. These chemistry questions are common in various competitive entrance examinations.

Ionic and covalent bondsHybridisation of elementsOctet rule exceptionsMolecular geometryIntermolecular forces

Chemical Bonding and Molecular Structure Questions

Multiple choice

What is the name of the compound Ca3N2?

  1. Nitrocalcium

  2. Calciumnitride

  3. Calcium nitrate

  4. Nitrous calcium
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Metal is written first, and then non-metal. Suffix '-ide' is added with the non-metal.

Multiple choice chemistry solid state imperfections in solids

The anionic sites occupied by unpaired electrons are called F-centers or colour centers. They impart ______ $(X)$ colour to the crystals on $NaCl.$ Excess of lithium makes $LiCl$ crystals ______ $(Y)$ and excess of potassium makes $KCl$ crystals ______ $(Z)$. $(X)$, $(Y)$ and $(Z)$ are:

  1. yellow, green and pink respectively.

  2. pink, yellow and violet (or lilac) respectively.

  3. yellow, pink and violet (or lilac) respectively.

  4. red, yellow and pink respectively,
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

$NaCl$ shows the metal excess defect, which results in the formation of an F-center in the crystal. When light falls on this crystal, the electron in F-center gets excited. This F-center is then responsible for the yellow $(X)$ color of $NaCl$.

In a similar way, the excess of lithium imparts Pink $(Y)$ colour of $LiCl$ crystals.
In a similar way, the excess of potassium imparts violet/lilac $(Z)$ colour of $KCl$ crystals.

Multiple choice chemistry solid state imperfections in solids

$F-$centres are :

  1. the electrons trapped in anionic vacancies

  2. the electron trapped in cationic vacancies

  3. non-equivalent sites of stoichiometric compound

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$F$-centres or colour centres are points in a crystalline compound at which negative ion missing is replaced by one or more unpaired electrons. 


Hence, they are electrons trapped in anionic vacancies.

Therefore, the option is A.

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).