List of top Chemistry Questions asked in Maharashtra Class XII

Calculate standard Gibbs energy change at 25°C for the cell reaction \( \text{Cd(s)} + \text{Sn}^{2+}(\text{aq}) \to \text{Cd}^{2+}(\text{aq}) + \text{Sn(s)} \), \( E^\circ_{\text{Cd}} = -0.403 \, \text{V} \), \( E^\circ_{\text{Sn}} = -0.136 \, \text{V} \).

Convert the following: 
i. Ethyl alcohol into ethyl acetate 
ii. Phenol into benzene 
iii. Diethyl ether into ethyl chloride

Write Dow process for preparation of Phenol. 
What is the action of bromine water on phenol? 
Give reason: Group 16th elements have lower ionisation enthalpy compared to group 15th elements. 
Write two uses of dioxygen. 
 

Derive relationship between \( \Delta H \) and \( \Delta U \) for gaseous reaction. Define: Vulcanization. What is peptide bond?

Define: Diastereoisomers. Give cis and trans isomers of [Co(NH3)4Cl2]+.
What is reference electrode?
Give reason : Bleaching action of ozone is also called dry bleach. 

Silver crystallizes in fcc structure. If edge length of unit cell is 400 pm, calculate density of silver (Atomic mass of Ag = 108). Write a note on Haloform reaction.
Draw labelled diagram of H\(_2\) – O\(_2\) fuel cell. Write two applications of fuel cell.
Explain Aldol condensation of ethanal.
Explain formation of [CoF\(_6\)]\(^{3-}\) complex with respect to:
i. Hybridisation
ii. Magnetic properties
iii. Inner/outer complex
iv. Geometry
Show that, time required for 99.9 percent completion of a first order reaction is three times the time required for 90 percent completion. Give electronic configuration of Gd (Z = 64). Write the name of nano structured material used in car tyres to increase the life of tyres.
Write chemical reactions for the following conversions:
i. Acetic acid into acetic anhydride
ii. Acetic acid into ethyl alcohol
Write IUPAC name and structure of methylphenylamine.
Explain anomalous behaviour of oxygen in group 16 with respect to:
i. Atomicity
ii. Magnetic property
iii. Oxidation state
Define Osmosis. How will you determine molar mass of non-volatile solute by elevation of boiling point?
2000 mmol of an ideal gas expanded isothermally and reversibly from 20 L to 30 L at 300 K, calculate the work done in the process (\( R = 8.314 \, \text{J K}^{-1} \text{mol}^{-1} \)).
Define Extensive property. Calculate the work done during the expansion of 2 moles of an ideal gas from 10 dm\(^3\) to 20 dm\(^3\) at 298 K in vacuum.
A weak monobasic acid is 10 percent dissociated in 0.05 M solution. What is percent dissociation in 0.15 M solution?
Write the reactions for the formation of nylon 6,6 polymer.
Draw structures of the following compounds:
i. Chloric acid
ii. Peroxydisulphuric acid
Define: Acidic buffer solution. Write the relationship between solubility and solubility product for PbI\(_2\).
Define: Green chemistry. Write two advantages of nanoparticle and nanotechnology.
Write chemical reaction for the preparation of glucose from sucrose. Write structure of D-ribose.
Explain the following terms:
i. Substitutional impurity defect
ii. Interstitial impurity defect
What is the action of the following reagents on ethyl amine:
i. Chloroform and caustic potash
ii. Nitrous acid
Write the chemical composition of cryolite.
Calculate molar conductivity for 0.5 M BaCl\(_2\) if its conductivity at 298K is 0.01 \( \Omega^{-1} \text{cm}^{-1} \).