SECTION - B [CHEMISTY - NUMERIC] - JEE STD 11 Science Questions

Question 14 Marks

A compound ' X ' absorbs 2 moles of hydrogen and ' X ' upon oxidation with $KMnO _4 \mid H ^{+}$gives

The total number of $\sigma$ bonds present in the compound ' X ' is __________.

Question 24 Marks

The bond dissociation enthalpy of $X _2 \Delta H _{\text {bond }}^{\circ}$ calculated from the given data is __________ $kJ mol ^{-1}$. (Nearest integer)
$\begin{array}{l} M ^{+} X ^{-}( s ) \rightarrow M ^{+}( g )+ X ^{-}( g ) \Delta H _{\text {lattice }}^{\circ}=800 kJ mol ^{-1} \\ M ( s ) \rightarrow M ( g ) \Delta H _{\text {sub }}^{\circ}=100 kJ mol ^{-1} \\ M ( g ) \rightarrow M ^{+}( g )^{-}+ e ^{-}( g ) \Delta H _{ i }^{\circ}=500 kJ mol ^{-1}\end{array}$
$
\begin{array}{l}
X(g)+e^{-}(g) \rightarrow X^{-}(g) \Delta H_{eg}^{\circ}=-300 kJ mol^{-1} \\
M(s)+\frac{1}{2} X_2(g) \rightarrow M^{+} X^{-}(s) \Delta H_{f}^{\circ}=-400 kJ mol^{-1}
\end{array}
$
[Given : $M ^{+} X ^{-}$is a pure ionic compound and X forms a diatomic molecule $X_2$ is gaseous state]

Answer

$\begin{aligned} \therefore \Delta H _{ f }( MX ) & =\Delta H _{\text {sub }}( M )+\text { I.E. }( M )+\frac{1}{2}[\text { B.E. }( X - X )] \\ & + EG ( X )+\text { L.E. }( MX )\end{aligned}$
$\begin{array}{l}-400=(100)+(500)+\frac{1}{2}(\text { B.E. })+(-300)+(-800) \\ \therefore \text { B.E. }=200 kJ mole ^{-1}\end{array}$

View full question & answer→

Question 34 Marks

When 81.0 g of aluminium is allowed to react with 128.0 g of oxygen gas, the mass of aluminium oxide produced in grams is __________. (Nearest integer)
Given :
Molar mass of Al is $27.0 g mol ^{-1}$
Molar mass of O is $16.0 g mol ^{-1}$

View full question & answer→

Question 44 Marks

Consider the following sequence of reactions.

Total number of $sp ^3$ hybridised carbon atoms in the major product C formed is __________ .

View full question & answer→

Question 54 Marks

0.01 mole of an organic compound $( X )$ containing $10 \%$ hydrogen, on complete combustion produced $0.9 g H _2 O$. Molar mass of $( X )$ is _________) $g mol ^{-1}$.

Answer

Organic compound $\xrightarrow{\text { combustion }} \underset{\substack{ H _2 O \\ 0.9 gm }}{ H _2}$
$\therefore$ mole of $H _2 O =\frac{0.9}{18}=0.05 mole$
$\therefore$ mole of H in $H _2 O =0.05 \times 2=0.1$ mole $=$ mole of H in 0.01 mole Organic compound
$\begin{aligned} \therefore \text { wt of } H \text { atom in } 0.01 \text { mole compound } & =0.1 \times 1 \\ & =0.1 gm \end{aligned}$
$\therefore$ wt of H atom in one mole compound $=\frac{0.1}{0.01}=10 gm$
$\because$ wt. $\%$ of $H =\frac{\text { wt. of } H \text { in one mole compound }}{\text { Molar mass of compound }} \times 1$
$\begin{array}{l}10=\frac{10}{ M } \times 100 \\ \therefore M =100\end{array}$

View full question & answer→

JEE SECTION - B [CHEMISTY - NUMERIC]

SECTION - B [CHEMISTY - NUMERIC]

Take a timed test