First Chapter Solved Exercise MCQs Of Fsc Second Year Chemistry

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First chapter Solved Exercise MCQs of 2nd-year chemistry

1: keeping in view the size of atoms which order is the correct one

  1. Mg > Sr
  2. Ba > Mg
  3. Lu > Ce
  4. Cl > I

Explanation

The correct answer is b

Because the sizes of atoms increase down the group and decrease along a period from left to right. Therefore, Br Ba should be greater than Mg. The reason is that Ba is higher in atomic number than Mg in group II-A.

2: Mark the correct statement

  1. Na+ is smaller than Na atom
  2. Na+ is larger than Na atom
  3. Cl– is smaller than Cl atom
  4. Cl– and Cl atom are equal in size

Explanation

The correct answer is a

Because the positively charged ions are always smaller than the neutral atoms due the increased attract between nucleus and outmost electron. Negatively charged ions are always greater than their neutral atoms due to increased force of repulsion between nucleus and outermost electron. Therefore Na+ is smaller than the Na atom.

3: Mark the correct statement

  1. All lanthanides are present in the same group
  2. All halogens are present in the same  group
  3. All the alkali metals are present in the same group
  4. All the noble gases are present in the same period
  5. Both B and C

Explanation

The correct answer is E

Because in the modern periodic table all the alkali metals are present in the same group I-A. Similarly halogens and noble gases also have their groups. Lanthanides are present in the sixth period of the periodic table. Therefore, option B and C are correct.

4: Which statement is incorrect

  1. All the metals are good conductor of electricity
  2. All the metals are good conductor of heat
  3. All the metals form positive ions
  4. All the metals form acidic oxides

Explanation

The correct answer is d

Because all the metals give basic oxides and acidic oxides are given by the non-metals

5: Which statement is correct?

  1. Hydrogen resembles in properties with I-A, IV-A and VII-A elements
  2. Hydrogen resembles in properties with III-A, IV-A and VI-A elements
  3. Hydrogen resembles in properties with II-A, IV-A and VI-A elements
  4. Hydrogen resembles in properties with II-A, III-A and VII-S elements

Explanation

The correct answer is A

Because the position of hydrogen in periodic table is debatable. It resembles in some of the properties with group I-A, IV-A and VII-A. Therefore the option A is correct.

6: Mark the correct statement

  1. The ionization energy of calcium is lower than that of Barium
  2.  The ionization energy of Calcium is lower than that of Magnesium
  3. The ionization energy of Calcium is higher than that of Beryllium
  4. The ionization energy of Calcium is lower than that of Strontium

Explanation

The correct answer is B

Because ionization energy decrease down the group. AS we know that calcium and Magnesium are present in the 2nd group. Calcium is higher in atomic number than Magnesium in group II-A. Therefore, size of Calcium is greater than that of Magnesium hence ionization energy of calcium is lower than that of Magnesium. Therefore the correct option is B.

7: Mark the correct statement

  1. Electron affinity is a measure of energy required to remove the electron
  2. Ionization energy is measure of energy release by adding an electron
  3. Electron affinity is a measure of energy required to excite an electron
  4. Electron affinity is measure of energy released by removing an electron
  5. None of these

Explanation

The correct answer is E

Because according to the definition of electron affinity is the energy released when an electron is added to an atom. All the above statement do not give this concept therefore all statements are wrong and the correct option is E.

8: Mark the incorrect statement

  1. Metallic character increases down the group
  2. Metallic character increases along a period
  3. Metallic character decreases along a period
  4. Metallic character remains the same down the group

Explanation

The correct answer is B

Because metallic character decreases along a period from left to right. It does not increase along a period. Therefore, the option B is incorrect.

9: Mark the correct statement

  1. Melting points of halogens decrease down the group
  2. Melting points of halogens increase down the group
  3. Melting points of halogens remain the same throughout the group
  4. Melting points of halogens first increase and then decrease down the group

Explanation

The correct answer is B

Because due to increased polarizabilities the melting point of halogens increase down the group. Therefore, the correct option B.

10: Mark the correct statement

  1. Covalent character of metal halides increase from left to right in a period
  2. Boiling points of group IV-A hydrides decrease down the group
  3. Ionic character of hydrides increase from left to right in a period
  4. The basicity of group IIA oxides decreases on descending the group

Explanation

The correct answer is A

Because the covalent character of metal halides increases from left to right in a period.