Aldehydes, Ketones and Carboxylic Acids — Chemistry STD 12 Science — Question

1. Write the steps involved in the preparation of: 

1. K₂Cr₂O₇ from Na₂CrO_4.
2. KMnO₄ from  K₂MnO_4.
3. Calomel from corrosive sublimate.

2. What is meant by lanthanoid contraction? What effect does it have on the chemistry of the elements which follow lanthanoids?

Explain the cyclic structure of glucose.

The decomposition of N₂O₅(g) is a first order reaction with a rate constant of 5 × 10^-4 s^-1 at 45°C, i.e., 2N₂O₅(g) → 4NO₂(g) + O₂(g). If initial concentration of N₂O₅ is 0.25M, calculate its concentration after 2min. Also, calculate half- life for decomposition of N₂O₅(g).

1.  

1. How is the variability in oxidation states of transition metals different from that of the p-block elements?
2. Out of Cu⁺ and Cu²⁺, which ion is unstable in aqueous solution and why?
3. Orange colour of Cr₂O₇^2– ion changes to yellow when treated with an alkali. Why?

2. Chemistry of actinoids is complicated as compared to lanthanoids. Give two reasons.

Match the items of Column I and Column II.

	Column I		Column II
i.	Lead storage battery	a.	Maximum efficiency.
ii.	Mercury cell	b.	Prevented by galvanisation.
iii.	Fuel cell	c.	Gives steady potential.
iv.	Rusting	d.	Pb is anode, PbO2 is cathode.

Describe how does the enthalpy of reaction remain unchanged when a catalyst is used in the reaction.

Explain valence bond theory for coordination compounds.

What is called a battery? Explain its characteristics and describe dry cell and mercury cell.

Give the electronic configuration of the following complexes on the basis of Crystal Field Splitting theory.
[CoF₆]^3-, [Fe(CN)₆]^4- and [Cu(NH₃)₆]²⁺