List of top Questions asked in CBSE CLASS XII

With increase in atomic number, the melting point of transition metals :
Write the reaction involved in the following :
Clemmensen reduction
An organic compound (X) having molecular formula C$_5$H$_{10$O can show various properties depending on its structures. Draw each of the structures if it :
shows Cannizzaro reaction.
Answer the following question:
Name two elements of 3d series for which the third ionisation enthalpies are quite high.
Complete the following ionic equations :
5SO$_3^{2-}$ + 2MnO$_4^-$ + 6H$^+$ ⟶ ?
Account for the following :
(I) The E$^\circ_{Mn^{2+}/Mn}$ value for manganese is highly negative, whereas E$^\circ_{Mn^{3+}/Mn^{2+}}$ is highly positive.
Calculate the emf of the following cell at 25$^\circ$C :
Zn(s) $\mid$ Zn$^{2+}$ (0.1 M) $\parallel$ H$^+$ (0.01 M) $\mid$ H$_2$(g) (1 bar), Pt(s)
Given: E$^\circ_{Zn^{2+}/Zn}$ = –0.76 V, E$^\circ_{2H^+/H_2}$ = 0.00 V, log 10 = 1
How can you convert propanenitrile to 1-aminopropane?

Write structure of the products of the following reactions:

Vinyl group directly attached with carboxylic acid should decrease acidity due to resonance, but it increases acidity. Explain.
Give reasons for the following:HCHO is more reactive than CH$_3$CHO towards addition of HCN.
Give reasons for the following:
Benzoic acid does not undergo Friedel-Crafts reaction.
Peptide linkage and Glycosidic linkage
Essential amino acids and Non-essential amino acids
Write two differences between Amylose and Amylopectin components of starch.
What is meant by negative deviation from Raoult’s law? Give an example. What type of azeotrope is formed by negative deviation?
Which of the following solution in water will have the lowest freezing point?
Among the following outermost electronic configurations of transition metals, which one shows the highest oxidation state?
What is cold sterilization ? List out the irradiation requirements for onions, potatoes, garlic and shallots, along with the purpose.
With the help of a flowchart, describe a method of cucumber pickles preparation.
What is bio-pesticide ? Classify the various bio-pesticides with example.
List out the main principles of organic farming.
Explain the different methods of fertilizer application.
Explain the various types of wheat flour and their use(s).
Why is there a need to preserve fruits and vegetables ?