Tag: chemistry

Questions Related to chemistry


An electrovalent bond is formed when a metal atom transfers one or more electrons to a non-metal atom in :

ionic bond atomic structure and chemical bonding chemistry

  1. ionic compounds

  2. covalent compounds

  3. metallic compounds

  4. crystalline solids

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Correct Option: A
Explanation:

An electrovalent bond is formed when a metal atom transfers one or more electrons to a non-metal atom and these compounds are called ionic compounds.

Pertaining to metallurgy, when "M" is a metal, its compound $MY _2$ is :

ionic bond atomic structure and chemical bonding chemistry

  1. Covalent

  2. Ionic

  3. Inorganic

  4. None of these

Show answer
Correct Option: B
Explanation:

Reaction:

$M-2e^- \rightarrow M^{2+}$

$2Y+2e^- \rightarrow 2Y^-$

$M^{2+} + 2Y^- \rightarrow MY _2$

So, this is an ionic compound.

In electrovalency:

ionic bond atomic structure and chemical bonding chemistry

  1. molecules lose electrons forming atoms

  2. molecules gain electrons forming atoms

  3. atoms share electrons

  4. atoms lose or gain electrons forming ions

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Correct Option: D
Explanation:

Electrovalency is shown by atoms when it looses or gains electrons in order to attain stability. Electrovalency is seen in ionic bonds. Electrovalency is equal to the number of electrons lost or gained by atom to form ion.

Example:- $CaCl _2$
Formation of $Ca^{2 _+}(Cl^-) _2$
Electrovalency of Calcium is $+2$ and is called positive electrovalency.
Electrovalency of Chlorine is $-1$ and is called negative electrovalency.

According to Coulomb's law, the force of attraction (F) between two oppositely charged ions separated by a distance d in air is given by

ionic bond atomic structure and chemical bonding chemistry

  1. $F = \dfrac {1}{4 \pi \epsilon _0 K} \times \dfrac {q _1q _2}{d^2}$

  2. $F = \dfrac {1}{4 \pi \epsilon _0 K} \times \dfrac {q _1q _2}{(r^+ + r^-)^2}$

  3. $F = {4 \pi \epsilon _0 K} \times \dfrac {q _1q _2}{d}$

  4. $F = {1}{4 \pi \epsilon _0 K} \times \dfrac {q _1q _2}{(r^+ + r^-)}$

Show answer
Correct Option: A,B
Explanation:

According to Coulomb's law, the force of attraction (F) between two oppositely charged ions separated by a distance d in air is given by
$F = \dfrac {1}{4 \pi \epsilon _0 K} \times \dfrac {q _1q _2}{d^2}$ or $F = \dfrac {1}{4 \pi \epsilon _0 K} \times \dfrac {q _1q _2}{(r^+  + r^-)^2}$

Which of the following factor(s) favour the formation of ionic bond?

ionic bond atomic structure and chemical bonding chemistry

  1. The electrostatic attraction between charged ions in the crystal (i.e, lattice energy) should be low.

  2. Both atoms should be equal in size.

  3. The combining elements should differ by at least 2.0 in electronegativity.

  4. The cation and anion should have inert gas electronic configuration.

Show answer
Correct Option: C,D
Explanation:

The following factors favour the formation of ionic bond.
The electrostatic attraction between charged ions in the crystal (i.e, lattice energy) should be high.
One of the atoms (metal) should be large in size. Other atom (non metal) should be small in size.
The combining elements should differ by at least 2.0 in electronegativity.
The cation and anion should have inert gas electronic configuration.

Which of the following represents true statement(s)?

ionic bond atomic structure and chemical bonding chemistry

  1. CsCl is more stable than NaCl because $(r _{Na+} + r _{Cl^-}) < (r _{Cs+} + r _{Cl^-}) $

  2. NaCl is more stable than CsCl because $(r _{Na+} + r _{Cl^-}) < (r _{Cs+} + r _{Cl^-}) $

  3. NaCl is more stable than MgO because the product of $q _1$ and $q _2$ in MgO is nearly four times to that in NaCl.

  4. MgO is more stable than NaCl because the product of $q _1$ and $q _2$ in MgO is nearly four times to that in NaCl.

Show answer
Correct Option: B,D
Explanation:

The options (B) and (D)  represents true statements.
NaCl is more stable than CsCl because $(r _{Na+} + r _{Cl^-}) < (r _{Cs+} + r _{Cl^-}) $
MgO is more stable than NaCl because the product of $q _1$ and $q _2$ in MgO is nearly four times to that in NaCl.
Note:
According to Coulomb's law, the force of attraction (F) between two oppositely charged ions separated by a distance d in air is given by $F

= \dfrac {1}{4 \pi \epsilon _0 K} \times \dfrac {q _1q _2}{d^2}$ or $F =

\dfrac {1}{4 \pi \epsilon _0 K} \times \dfrac {q _1q _2}{(r^+  + r^-)^2}$

In the atom of an element X, 6 electrons are present in the outermost shell. If it acquires noble gas configuration by accepting requisite number of electrons, then what would be the charge on the ion so formed?

ionic bond atomic structure and chemical bonding chemistry

  1. 1

  2. 2

  3. 3

  4. 4

Show answer
Correct Option: B
Explanation:

Electronic configuration of noble gas is $\mathrm{(2,8)}$. It has $\mathrm{8}$ electron in its outermost orbitals.
Element X has $\mathrm{6}$ electrons in its outermost shell. So, it requires $\mathrm{2}$ more electrons to attain the noble gas configuration.
Hence, option $\mathrm{B}$ is the correct answer.

The charged particles that attract each other to form electrovalent compounds are _________.

ionic bond atomic structure and chemical bonding chemistry

  1. Protons and neutrons

  2. Cation and anion

  3. Electrons

  4. none of these

Show answer
Correct Option: B
Explanation:

Cation$\rightarrow $positively charged

Anion$\rightarrow $negatively charged
           Negative charges attract each other
Cation and onion are the charged particles that attract each other to form electrovalent compounds.

When dealing with a spillage of metallic sodium it is important that no toxic or flammable products are formed.
Which material should be used if there is a spillage of metallic sodium?

chemistry the s-block elements (alkali and alkaline earth metals) biological importance of sodium and potassium biological importance of elements biological importance of s block elements

  1. Dilute hydrochloric acid

  2. Ethanol

  3. Sand

  4. Water spray

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Correct Option: C
Explanation:

Sand can be used if there is a spillage of metallic sodium as sand will have no reaction with sodium metal and it serves as a coating to protect sodium from any reaction.

Select the incorrect statement:

chemistry the s-block elements (alkali and alkaline earth metals) biological importance of sodium and potassium biological importance of elements biological importance of s block elements

  1. sodium and potassium are $6$th and $7$th most abundant element in the earth's crust

  2. $NaOH$ is hygroscopic in nature

  3. if a crystal of $NaOH$ is exposed to air for longer periods it potassium a white powder of $Na _{2}CO _{3}$

  4. lithium is an alkali metal and can be used in photoelectric cells

Show answer
Correct Option: D
Explanation:
Among alkali metals, cesium has lowest ionisation enthalpy and hence it can show photoelectric effect to the maximum extent and therefore preffered in photoelectric cell. The alkali metal widely used in photoelectric cell is Cs
Alkali metals have lower ionisation energy than their counterparts and hence havemhigher chance of emitting electrons, when  a radiation falls on them. So they are used in photoelectric cells so that they easily emit electron when energy containing photons in sunlight strikes them.
Hence option D is incorrect statement