Fourth Chapter Solved Exercise MCQs Of Fsc Second Year Chemistry

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Third Chapter Solved Exercise MCQs Of Fsc Second Year Chemistry

1: Out of all the elements of group V-A, the highest ionization energy is possessed by

  1. N
  2. P
  3. Sb
  4. Bi

Explanation

As we know that ionization energy decreases down the group. Therefore, the highest ionization energy is shown by nitrogen because it is the first member of the series.

2: In group V-A elements the most electronegative element is

  1. Sb
  2. N
  3. P
  4. As

Explanation

As we know that electronegativity decreases down the group. Therefore, nitrogen being the first member of the group V-A is the most electronegative element.

Also read

First Chapter Solved Exercise MCQs Of Fsc Second Year Chemistry

Second Chapter Solved Exercise MCQs Of Fsc Second Year Chemistry

Third Chapter Solved Exercise MCQs Of Fsc Second Year Chemistry

3: Oxidation of NO in air produces

  1. N2O
  2. N2O3
  3. N2O4
  4. N2O5

Explanation

Oxidation mean increase in oxidation number. Therefore, when NO is oxidized in air then oxygen is oxidized to produce N2O4.

4: The brown gas formed when metal reduces HNO3 is

  1. N2O5
  2. N2O3
  3. NO2
  4. NO

Explanation

When some metals react with HNO3, they reduce the HNO3 into their oxides like N2O, NO, and NO2. Among all the three gases NO2 is brown colored gas.

5: Laughing gas is chemically

  1. NO
  2. N2O
  3. NO2
  4. N2O4

Explanation

Among all the above mentioned oxides of nitrogen N2O is a gas that produces a hysterical laughter. Therefore N2O is called laughing gas.

6: Out of all the elements of group VIA the highest melting and boiling point is shown by the element

  1. Te
  2. Se
  3. S
  4. Po

Explanation

Out of all the elements of group VI-A, Po shows highest melting and boiling points.

7: SO3 is not absorbed in water directly to form H2SO4 because

  1. The reaction does not go to completion
  2. The reaction is quite slow
  3. The reaction is exothermic
  4. SO3 is insoluble in water

Explanation

SO3 is not directly absorbed in water to form H2SO4, because the reaction is highly exothermic. Therefore, option c is the correct answer.

8: Which catalyst is used in contact process?

  1. Fe2O3
  2. V2O5
  3. SO3
  4. Ag2O

Explanation

In the contact process for the manufacture of H2SO4, V2O5 is used as a catalyst.

9: Which of the following specie has the maximum number of unpaired electrons?

  1. O2
  2. O2+
  3. O2-
  4. O2-2

Explanation

The molecule of O2 has two unpaired electrons in the outermost antibonding molecular orbitals.

In case of O2-2 There are no unpaired electrons because the incoming electrons are paired up with those two electrons which are already present.

In case of O2-1 there is one unpaired electron.

In case of O2+1 there is again one unpaired electron. SO the specie having maximum numbers of unpaired electrons is O2.

Have a look at this electronic configuration of O2.

1s2s2px2py2pz
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