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Coordination Compounds — Chemistry STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceChemistryCoordination Compounds4 Marks
Question
Read the passage given below and answer the following questions:
Werner, a Swiss chemist in $1892$ prepared and characterised a large number of coordination compounds and studied their physical and chemical behaviour. He proposed that, in coordination compounds, metals possess two types of valencies, viz. primary valencies, which are normally ionisable and secondary valencies which are non-ionisable. ln a series of compounds of cobalt (III) chloride with ammonia, it was found that some of the chloride ions could be precipitated as $AgCl$ on adding excess of $AgNO_3$ solution in cold, but some remained in solution. The number ofions furnished by a complex in a solution can be determined by precipitation reactions. The measurement of molar conductance of solutions of coordination compounds helps to estimate the number of ions furnished by the compound in solution.
In these questions (Q. No. i-iv), a statement of assertion followed by a statement ofreason is given. Choose the correct answer out of the following choices.
  1. Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. Assertion and reason both are correct statements but reason is not correct explanation for assertion.
  3. Assertion is correct statement but reason is wrong statement.
  4. Assertion is wrong statement but reason is correct statement.
The following questions are multiple choice questions. Choose the most appropriate answer:
  1. Assertion: The complex $[Co(NH_3)_3Cl_3]$ does not give precipitate with silver nitrate solution.
Reason: The given complex is non-ionisable.
  1. Assertion: The complex $[Co(NH_3)_4Cl_2]Cl$ gives precipitate corresponding to 2 mol of AgCl with $AgNO_3$ solution.
Reason: It ionises as $[Co(NH_3)_4Cl_2]^+ + Cl^-.$
  1. Assertion: $CoCl_3. 4NH_3$ gives 1 mol of AgCl on reacting with $AgNO_3$​​​​​​​, its secondary valency is 6.
Reason: Secondary valency corresponds to coordination number.
  1. Assertion: 1 mol of $[CrCl_2(H_2O)_4]Cl· 2H_2O$ will give 1 mol of AgCl on treating with $AgNO_3$​​​​​​​.
Reason: $Cl^-$ ions satisfying secondary valanceis will not be precipitated.
  1. Assertion: $CoCl_3. 3NH_3$ is not conducting while $CoCl_3. 5NH_3$​​​​​​​ is conducting.
Reason: The complex of $CoCl_3. 3NH_3$ is $[CoCl_3(NH_3)_3]$ while that of $CoCl_3· 5NH_3$ is $[CoCl(NH_3)_5]Cl_3$.
✓

Answer

  1. (a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
  2. (d) Assertion is wrong statement but reason is correct statement.
Explanation:

$[\text{Co(NH}_3)_4\text{Cl}_2]\text{Cl}+\text{AgNO}_3\rightarrow[\text{Co(NH}_3)_4\text{Cl}_2]^++\text{AgCl}\downarrow$

Thus it gives precipitate of 1 mol of AgCI.
  1. (b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
Explanation:

$CoCl_3$. $4NH_3$ gives 1 mol AgCl on reaction with $AgNO_3$, hence the complex can be represented as $[CoCl_2(NH_3)_4]CI$.
  1. (a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
Explanation:

The $Cl^-$ ions outside the coordination sphere can only be precipitated.
  1. (a) Assertion and reason both are correct statements and reason is correct explanation for assertion.

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  4. Assertion is wrong statement, but reason is correct statement.
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  4. Assertion is wrong statement but reason is correct statement.
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  4. Both have ABCABC... Arrangement.
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  3. The number of Bravais lattice in which a crystal can be categorized is 7.
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The following questions are multiple choice questions. Choose the most appropriate answer:
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  1. $8, 6$
  2. $6, 4$
  3. $6, 8$
  4. $4, 6$
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  2. $0.732$
  3. $0.225$
  4. $0.155$
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  1. $6$
  2. $4$
  3. $8$
  4. $12$
  1. Which is not the correct statement for ionic solids, in which positive and negative ions are held by strong electrostatic attractive forces?
  1. The radius ratio $\frac{\text{r}_+}{r}$ increases as coordination number increases.
  2. As the difference in size of ions increases, coordination number increases.
  3. When coordination number is eight, $\frac{\text{r}_+}{r}$ ratio lies between $0.225$ to $0.414.$
  4. In ionic solid of the type AX (ZnS, wurtzite), the coordination number of $Zn^2$ and $S^2$- respectively are $4 $and $4.$
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  3. Decrease
  4. None of these.
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