Biomolecules — Chemistry STD 12 Science — Question

1. Following are the transition metal ions of 3d series:

Ti⁴⁺, V²⁺, Mn³⁺, Cr³⁺

(Atomic numbers : Ti = 22, V = 23, Mn = 25, Cr = 24)

Answer the following:

1. Which ion is most stable in an aqueous solution and why?
2. Which ion is a strong oxidising agent and why?
3. Which ion is colourless and why?

2. Complete the following equations:

1. $2\text{ }\text{MnO}_4^-+16\text{ }\text{H}^++5\text{ }\text{S}^{2-}\xrightarrow{\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }\text{ }}$

2. $\text{KMnO}_4\xrightarrow{\text{ }\text{ }\text{ }\text{ }\text{ }\text{heat}\text{ }\text{ }\text{ }\text{ }\text{ }}$

1. Complete the following chemical equations:

1. $ \text{MnO}_{4}^{-}\text{(aq)}+\text{S}_{2}\text{O}_{4}\text{(aq)}+\text{H}_{2}\text{O}\text{(l)}\rightarrow$
2. $\text{Cr}_{2}\text{O}_{4}^{2-}\text{(aq)}+\text{Fe}^{2+}\text{(aq)}+\text{H}^{+}\text{(aq)}\rightarrow$

2. Explain the following observations:

1. La³⁺ (Z = 57) and Lu³⁺ (Z = 71) do not show any colour in solutions.
2. Among the divalent cations in the first series of transition elements, manganese exhibits the maximum paramagnetism.
3. Cu⁺ ion is not known in aqueous solutions.