Solid State - ISC Class 12 Chemistry Questions with Answers, Page 2

Match the following:

Fill in the blanks by choosing the appropriate word/words from those given in the brackets: (increases, decreases, efficient, same as, 68, non-efficient, greater than, 74, less than, $sp^3d^3$, $sp^3d^2$, octahedral, distorted octahedral, remains same) (i) Both ccp and hcp are _______ close packing and occupy about _______% of the available space. (ii) The molar conductance of a solution _______ with dilution, while its specific conductance _______ with dilution. (iii) The geometry of $\text{XeF}_6$ molecule is _______ and the hybridization of Xe atom in the molecule is _______. (iv) The acidic strength of phenol is _______ ethyl alcohol but _______ nitro phenol.

Complete the following statements by selecting the correct alternative from the choices given: (i) The molal freezing point constant of water is $1\cdot86\text{ K kg mol}^{-1}$. Therefore, the freezing point of $0\cdot1\text{ M NaCl}$ solution in water is expected to be: (1) $-1\cdot86^\circ\text{C}$ (2) $-0\cdot372^\circ\text{C}$ (3) $-0\cdot186^\circ\text{C}$ (4) $+0\cdot372^\circ\text{C}$ (ii) Which among the following reacts fastest by $\text{S}_\text{N}2$ reaction: (1) $(\text{CH}_3)_3\text{C}-\text{Br}$ (2) $(\text{CH}_3)_2\text{CH}-\text{Br}$ (3) $\text{CH}_3-\text{CH}_2-\text{Br}$ (4) $\text{CH}_3-\text{Br}$ (iii) When acetaldehyde is treated with Grignard reagent followed by hydrolysis, the product formed is: (1) Primary alcohol (2) Secondary alcohol (3) Carboxylic acid (4) Tertiary alcohol (iv) Which of the following ores can be concentrated by froth floatation process: (1) Haematite (2) Calamine (3) Zinc blende (4) Bauxite

Answer the following questions: (i) Calculate the mass of compound (molar mass = $256\text{ g mol}^{-1}$) to be dissolved in $75\text{ g}$ of benzene to lower its freezing point by $0\cdot48\text{ K}$ ($K_f = 5\cdot12\text{ K kg mol}^{-1}$). (ii) Write the IUPAC name of the complex $[\text{Cr}(\text{NH}_3)_4\text{Cl}_2]^+$. Which type of isomerism will be exhibited by it? (iii) Why do the transition elements have higher enthalpies of atomisation? In 3d series (Sc to Zn), which element has the lowest enthalpy of atomisation and why? (iv) Write balanced chemical equations for Carbylamine reaction and Diazotization reaction.

Complete the following statements by selecting the correct alternative from the choices given: (i) During the course of an $\text{S}_\text{N}1$ reaction, the intermediate species formed is: (1) a carbocation (2) a free radical (3) a carbanion (4) an intermediate complex (ii) Purification of aluminium by electrolytic refining is called: (1) Serpeck’s process (2) Hoope’s process (3) Hall’s process (4) Baeyer’s process (iii) An aqueous solution of urea freezes at $-0\cdot186^\circ\text{C}$, $K_f$ for water = $1\cdot86\text{ K kg mol}^{-1}$, $K_b$ for water = $0\cdot512\text{ K kg mol}^{-1}$. The boiling point of urea solution will be: (1) $373\cdot065\text{ K}$ (2) $373\cdot186\text{ K}$ (3) $373\cdot512\text{ K}$ (4) $373\cdot0512\text{ K}$ (iv) In the dehydration of alcohols to alkenes by heating with concentrated sulphuric acid, the initiation step is: (1) formation of carbocation (2) formation of an ester (3) protonation of alcohol molecule (4) elimination of water