Important Questions Class XII Chemistry (2009) Set - VII

Chemistry

Q. 105. Write the ground state electronic configuration of N₂.

1. Determine the bond order of N₂.
2. N2 and CO has same bond order, but CO is more reactive than N2. Why?

Q. 106.An element A crystallizes in FCC structure. 200g of this element has 24x1023 atoms. Density of unit cell is 7.2g/cm3. Calculate the radius of A. Avogadro number= 6x 1023 mole- 1

Q. 107. The activation energy of a first order reaction at 270C is 54 KJ/mole. Activation energy of the same reaction at the same temperature in the presence of a catalyst is 44 KJ/mole. How many times the reaction rate changes in the presence of catalyst at this temperature? (R=8.314J/K/mole)

Q. 108. 0.85% solution of NaNO3 is 90% dissociated at 300K.Determine the somatic pressure of the solution.( R= 0.0821 L atm/K/mole. Molar mass of NaNO3=85u) OR Determine the boiling point of 1M solution of KCl. Assume that KCl is 90% dissociated. Density of KCl solution is 1.05g/cm3. Molar mass of KCl=74.5u. Kb= 0.52 K Kg mole

Q. 109.

1. Predict the sign of entropy change for the reaction CaCO3(s)®CaO(s) +CO2(g)
2. You are provided with the following DrG0 values S2 +2 O2 ® 2SO2 DrG0 = - 544 KJ/mole 2Zn +O2® 2ZnO DrG0 = - 480 KJ/mole 2Zn+ S2 ® 2ZnS DrG0 = - 293 KJ/mole Show that roasting of ZnS to ZnO is a spontaneous process.

Q. 110. Explain the terms activity and selectivity of catalyst with examples.

Q. 111

1. How is potassium dichromate prepared from chromate ore?
2. Write the ionic equation of the reaction involved when KMnO4 is treated with ferrous sulphate solution in acid medium.

Q. 112. Using Valence bond theory compare the structure and magnetic behavior of.

1. Ni (CO)₄
2. [Ni (CN)4]₂- Atomic number of Ni=28

Q. 113.

1. A radio active element of group 18 undergoes a decay. Determine the position ofthe new nuclide.
2. Calculate the mass of 140 La in a sample whose activity is 3.7x1010Bq. Given half life of 140 La = 40 hours.

Q. 114. Carry out the following conversions:

1. Benzoyl chloride to benzaldehyde.
2. Hex-1-ene to pentanal
3. Hexane nitrile to 1-amino pentane.

Q. 115. Account for the following:

1. In ammonalysis of halo alkanes primary amine is the only product when NH₃is taken in large excess.
2. Tert amine has lower boiling point than primary amine of comparable molar mass,
3. Amide formed in acylation reaction of amine, does not react further with acid halide.

Q. 116. Describe the following with suitable examples:

1. Double base propellant
2. Mordant dyes
3. Broad spectrum antibiotics.

Q. 117.

1. Explain corrosion of iron as an electro chemical process.
2. The electrolysis of a metal salt solution was carried out by passing 4 amperes for 45 minutes. It resulted in the deposition of 2.977g of the metal. If atomicmass of the metal is 106.4g/mole, determine the charge carried by the metal ion.

OR

1. How does conductivity and molar conductivity of an electrolyte solution vary with the dilution of the solution.
2. The E0 potentials of two reduction electrodes are Cu+/ Cu = + 0.52V and Cu2+ / Cu+ = + 0.16 V. Calculate the work obtainable from the cell.

Q. 118. (a) Account for the following:

1. PCl₅ solid is ionic in nature.
2. SF₆ is resistant to hydrolysis.
3. Inter halogen compounds are more reactive than halogens from which it is made.

(b) Draw the structures of the molecules

1. P₄O₁₀
2. per oxo mono sulphuric acid.

OR

(a) Account for the following:

1. PCl₅ fumes in air.
2. Ga is smaller in size than Al.
3. PbO₂ is a good oxidizing agent.

(b) Draw the structures of the molecules

1. SF4
2. IF4¯

Q. 119.

1. what are lipids? Based on their chemical composition, present a classification of lipids.
2. In reference to DNA molecule what do you under stand by the terms replication and transcription.

OR

1. Define the terms (i) codon (ii) native state of protein (iii) Denaturation of protein.
2. Write the name of the nucleoside which is present only in (i) DNA (ii) RNA.

Q. 120. Define activation energy of a reaction.

Q. 121. A cubic solid is made of two elements X and Y. Atoms Y are at the corners of the cube and X at the body centre. What is the formula of the compound?

Q. 122. State two main functions of carbohydrates in sugarcane.

Q. 123. Why is HF not stored in plain glass bottles?

Q. 124. State one use of acetonitrile.

Q. 125. What values of quantum number, m are permitted for an electron having angular quantum number, 1 = 2 ?

Q. 126. Which types of crystals exhibit piezoelectricity?

Q. 127. What is Tyndall effect?

Q. 128. How many effective sodium ions are located at the centers of faces of a unit cell in a sodium chloride crystal?

Q. 129. Name the first element of 3 d transition metal series.

Q. 130. What are inner transition metals?

Q. 131. State second law of thermodynamics.

Q. 132. Name a direct dye.

Q. 133. Sketch the zwitter ion form of amino acetic acid.

Q. 134. Mention an industrial product manufactured from methanal.

Q. 135. How does a fuel cell operate?

Q. 136. Mention two important uses of methanol.

Q. 137. What is the importance of amino acids to us?

Q. 138. Give an example of associated colloids.

Q. 139. Define order of a reaction.

Q. 140. Zn, Cd and Hg are not considered as transition metals.

Q. 141. Cu,Ag &Au are considered as transition metal though it has 3d,10 configuration.

Q. 142. Zn, Cd and Hg are volatile and Hg is a liquid metal.

Q. 143. Transition metals have high enthalpy of atomisation.

Q. 144. 4d and 5d elements have higher enthalpy of atomisation than 3d elements.

Q. 145. Density of 3d elements increases from Sc to Ni.

Q. 146. Atomic and ionic radii generally decrease along the period.

Q. 147. Zr and Hf have similar size.

Q. 148. Transition metals do not show regular variation of ionisation enthalpies.

Q. 149. 5d elements have higher ionisation enthalpy than 3d and 4d elements.

Q. 150. Generally first ionisation enthalpy increases along the period.