Tag: chemistry

Questions Related to chemistry

Substance which vaporize during burning gives ____________.

chemistry combustion and flame structure of flame flame combustion

  1. sound

  2. flame

  3. combustion

  4. none of these

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Correct Option: B
Explanation:

Substances which vaporize during burning gives flame. For example, combustion of kerosene oil produces a flame. On the other hand, certain substances like coal do not vaporize and hence does not produce a flame.

Innermost zone is the _______.

chemistry combustion and flame structure of flame flame combustion

  1. hottest part

  2. moderately hot part

  3. least hot part

  4. cold part

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Correct Option: C
Explanation:

The innermost zone is the least hot part black in colour. This is due to the unburned wax vapor.

Yellow colour in the flame denotes __________.

chemistry combustion and flame structure of flame flame combustion

  1. outermost part

  2. middle zone

  3. innermost zone

  4. none of these

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Correct Option: B
Explanation:

The middle zone is moderately hot and is yellow in color. This is because of partial combustion.

The stability of an ionic compound is mostly due to:

chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

  1. ionization energy

  2. electron affinity

  3. lattice energy

  4. electronegativity

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Correct Option: C
Explanation:

Lattice energy is a measure of energy released in ionic crystals when the ions are brought together from infinity. It measures the attraction between ions so that they are held in a position. Ionic compound stability is mostly due to lattice energy.

Decreasing order of lattice energy of $FeO, Fe _2O _3, NaCl$ is:

chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

  1. $NaCl>FeO>Fe _2O _3$

  2. $Fe _2O _3>FeO>NaCl$

  3. $NaCl>FeO=Fe _2O _3$

  4. $Fe _2O _3>NaCl>FeO$

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Correct Option: B

The magnitude of the lattice energy of a soild increases if:

chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

  1. the ions are large

  2. the ions are small

  3. the ions are of equal size

  4. charges on the ions are small

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Correct Option: B
Explanation:

Lattice energy is directly proportional to the charge on the ions and inversely proportional to the size of the ions.  Smaller the size, greater is the lattice energy.

The higher lattice energy corresponds to 

chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

  1. ${\rm{MgO}}$

  2. ${\rm{CaO}}$

  3. $4{\rm{SrO}}$

  4. ${\rm{BaO}}$

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Correct Option: B

Maximum lattice enthalpy is present in

chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

  1. $K _{2}O$

  2. $CaO$

  3. $Al _{2}O _{3}$

  4. $KCl$

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Correct Option: D

The melting point of a material with low binding energy is:

chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

  1. high

  2. low

  3. infinity

  4. negative

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Correct Option: B
Explanation:

The melting point of a material with low binding energy is low. When, the binding energy is low, the attraction between the valence electron and the nucleus is low. This also means that the intermolecular attraction is low. Hence, the melting point is low.

Which pair is not correct order of lattice energy?

chemistry lattice energy defining lattice energy ionic or electrovalent bond energy cycles

  1. $KCI > MgO$

  2. $AlN > MgO$

  3. $BeCO _3 > MgCO _3$

  4. $KCI < MgO$

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Correct Option: A
Explanation:

Lattice Energy is directly proportional to the charge on the ions and inversely proportional the size of the ions. As size decreases, lattice energy increases. So $MgO$ have higher lattice energy than $KCl$.