Question 1 :
For making good quality mirrors, plates of float glass are used. These are obtained by floating molten glass over a liquid metal which does not solidify before glass. The metal used can be

Question 2 :
The stability of dihalides of {tex}\mathrm{Si, Ge, Sn}{/tex} and {tex}\mathrm{Pb}{/tex} increases steadily in the sequence

Question 3 :
{tex} \mathrm { B } ( \mathrm { OH } ) _ { 3 } + \mathrm { NaOH } \rightarrow \mathrm { NaBO } _ { 2 } + \mathrm { Na } \left[ \mathrm { B } ( \mathrm { OH } ) _ { 4 } \right] + \mathrm { H } _ { 2 } \mathrm { O } {/tex}<br>How can this reaction is made to proceed in forward direction?

Question 4 :
Which of the following statement(s) is/are incorrect?<br>(i) Higher boranes are not flammable.<br> (ii) Boranes are hydrolysed by water to give orthoboric acid.?<br> (iii) Boranes undergoes cleavage reactions with Lewis bases to give borane adducts.<br>

Question 8 :
Carbon and silicon belong to group {tex} 14 . {/tex} The maximum coordination number of carbon in commonly occurring compounds is {tex} 4 , {/tex} whereas that of silicon is {tex} 6 . {/tex} This is due to

Question 9 :
Which of the following is/are not correctly matched?<br>(i) {tex} \mathrm { GeO } _ { 2 } {/tex} - Acidic <BR>(ii) {tex} \mathrm { PbO } _ { 2 } - {/tex} Amphoteric<BR> (iii) {tex} \mathrm { CO } - {/tex} Neutral <BR>(iv) {tex} \mathrm { SiO } _ { 2 } - {/tex} Amphoteric<br>

Question 10 :
Choose the correct sequence for the geometry of the given molecules Borazone, Borazole, {tex} \mathrm { B } _ { 3 } \mathrm { O } _ { 6 } ^ { 3 - } {/tex} [P' stands for planar and "N' stands for non- planar]

Question 11 :
{tex} \mathrm { Al } _ { 2 } \mathrm { O } _ { 3 } {/tex} can be converted to anhydrous {tex}\mathrm{AlCl} _ { 3 } {/tex} by heating

Question 12 :
In view of the signs of {tex} \Delta _ { r } G ^ { \circ } {/tex} for the following reactions:<br>{tex} \begin{array} { l l } { \mathrm { PbO } _ { 2 } + \mathrm { Pb } \rightarrow 2 \mathrm { PbO } , } & { \Delta _ { r } \mathrm G ^ { \circ } < 0 } \\ { \mathrm { SnO } _ { 2 } + \mathrm { Sn } \rightarrow 2 \mathrm { SnO } , } & { \Delta _ { r } \mathrm G ^ { \circ } > 0 } \end{array} {/tex}<br>Which oxidation states are more characteristics for lead and {tex} \operatorname { tin } ? {/tex}

Question 13 :
Often a ground glass stopper gets stuck in the neck of a glass bottle containing {tex}\mathrm{NaOH}{/tex} solution. This is due to :

Question 15 :
Which one of the following is a correct set for {tex} \mathrm { SiO } _ { 2 } ? {/tex}

Question 17 :
{tex}\mathrm{AlF_{3}}{/tex} is soluble in {tex}\mathrm{HF}{/tex} only in presence of {tex}\mathrm{KF}{/tex}. It is due to the formation of

Question 18 :
In the following sets of reactants which two sets best exhibit the amphoteric characters of<br>{tex} \mathrm { Al } _ { 2 } \mathrm { O } _ { 3 } \cdot \mathrm { xH } _ { 2 } \mathrm { O } ? {/tex}<br>Set {tex} 1: \mathrm { Al } _ { 2 } \mathrm { O } _ { 3 } \cdot \mathrm { xH } _ { 2 } \mathrm { O } ( \mathrm { s } ) {/tex} and {tex} \mathrm { OH } ^ { - } ( \mathrm { aq } ) {/tex}<br> Set {tex} 2: \mathrm { Al } _ { 2 } \mathrm { O } _ { 3 } \cdot \mathrm { xH } _ { 2 } \mathrm { O } ( \mathrm { s } ) {/tex} and {tex} \mathrm { H } _ { 2 } \mathrm { O } ( \mathrm { l } ) {/tex}<br> Set {tex} 3: \mathrm { Al } _ { 2 } \mathrm { O } _ { 3 } \cdot \mathrm { xH } _ { 2 } \mathrm { O } ( \mathrm { s } ) {/tex} and {tex} \mathrm { H } ^ { + } ( \mathrm { aq } ) {/tex}<br> Set {tex} 4: \mathrm { Al } _ { 2 } \mathrm { O } _ { 3 } \cdot \mathrm { xH } _ { 2 } \mathrm { O } ( \mathrm { s } ) {/tex} and {tex} \mathrm { NH } _ { 3 } ( \mathrm { aq } ) {/tex}

Question 19 :
Bauxite ore is generally contaminated with impurity of oxides of two elements {tex}\mathrm X {/tex} and {tex}\mathrm Y . {/tex} Which of the following statement is correct?

Question 20 :
Which of the following species exists (A) {tex} \left[ \mathrm { SiF } _ { 6 } \right] ^ { 2 - } , {/tex} (B) {tex} \left[ \mathrm { GeCl } _ { 6 } \right] ^ { 2 - } {/tex} and (C) {tex} \mathrm { } \left[ \mathrm { CCl } _ { 6 } \right] ^ { 2 - } ? {/tex}

Question 21 :
What is the oxidation state and hybridisation of boron in compound formed when {tex} \mathrm { BCl } _ { 3 } {/tex} undergoes reaction with the water?

Question 23 :
Which of the following statements are correct?<br>(i) Aluminium forms {tex} \left[ \mathrm { AlF } _ { 6 } \right] ^ { 3 - } {/tex} ion while boron forms only {tex} \left[ \mathrm { BF } _ { 4 } \right] ^ { - } {/tex} ion due to presence of {tex} d {/tex} -orbitals in aluminium.<br> (ii) The first member of a group differs from the heavier members in its ability to form p{tex} \pi {/tex} -p{tex}\pi {/tex} multiple bonds to itself and to other second row elements. While heavier member forms d{tex} \pi {/tex} -p{tex}\pi {/tex} bonds.<br>(iii) {tex} d {/tex} -orbitals contribute more to the overall stability of molecules than p{tex} \pi {/tex}-p{tex} \pi {/tex} bonds. bonding of second row elements.

Question 26 :
Anhydrous {tex}\mathrm{ AlCl} _ { 3 } {/tex} cannot be obtained from which of the following reactions?

Question 29 :
Aluminium is extracted from alumina {tex} \left( \mathrm { Al } _ { 2 } \mathrm { O } _ { 3 } \right) {/tex} by electrolysis of a molten mixture of:

Question 30 :
The gas evolved on heating {tex} \mathrm {CaF}_2{/tex} and {tex} \mathrm { SiO } _ { 2 } {/tex} with concentrated {tex} \mathrm { H } _ { 2 } \mathrm { SO } _ { 4 } , {/tex} on hydrolysis gives a white gelatinous precipitate. The precipitate is: