Covalent Character

Q. The correct sequence of bond enthalpy of ${}^{\prime }C—X^{\prime }$ bond is :

1. $C{H}_3–Cl>C{H}_3–F>C{H}_3–Br>C{H}_3–l$
2. $C{H}_3–F<C{H}_3–Cl<C{H}_3–Br<C{H}_3–l$
3. $C{H}_3–F>C{H}_3–Cl>C{H}_3–Br>C{H}_3–l$
4. $C{H}_3–F<C{H}_3–Cl>C{H}_3–Br>C{H}_3–l$

Q. The correct order of bond dissociation enthalpy of halogen is:

1. $F_2>C{l}_2>B{r}_2>I_2$
2. $C{l}_2>F_2>B{r}_2>I_2$
3. $C{l}_2>B{r}_2>F_2>I_2$
4. $I_2>B{r}_2>C{l}_2>F_2$

Q.

Assertion: All the collisions of the reactant molecules lead to product formation.

Reason: Only those collisions in which the molecules have the correct orientation and sufficient kinetic energy lead to compound formation.

1. Both assertion and reason are correct and the reason is correct explanation of assertion.

2. Assertion is correct but reason is incorrect.

3. Both assertion and reason are correct but reason does not explain assertion.

4. Assertion is incorrect but reason is correct.

5. Both assertion and reason are incorrect.

Q. how C=O bond having a highest bond energy

Q. Scandium does not exhibit variable oxidation states and yet it is regarded as a transition element. Give reason.

Q. Choose the correct order for the energy barrier to rotation around the B-N bond :- Options 1. H2B–NR2 < BH(NR2)2 < B(NR2)3 2. B(NR2)3 < BH(NR2)2 < BH2–NR2 3. BH(NR2)2 > B(NR2)3 > BH2–NR2 4. BH2–NR2 > B(NR2)3 > BH(NR2)2

Q. A compound of vanadium possess a magnetic moment of 1.73 B.M. What is the oxidation state of vanadium in the compound

Q. Aluminium is usually found in +3 oxidation state. In contrast, thallium exists in +1 and +3 oxidation states. This is due to:

1. lanthanoid contraction
2. lattice effect
3. diagonal relationship
4. inert pair effect

Q. Carbon and silicon belong to the ${14}^{th}$ group. The maximum coordination number of carbon in commonly occurring compounds is 4, whereas that of silicon is 6. This is due to:

1. the availability of low energy d-orbitals in silicon
   
2. more electropositive nature of silicon
3. large size of silicon
   
4. both (b) & (c)

Q.

Which of the following has least bond dissociation energy ?

1. Cl₂

2. F₂

3. Br₂

4. I₂

Q. As the oxidation number of a transition metal in transition metal oxide increases, the melting point

1. Increases
2. Decreases
3. Remains the same
4. Cannot be predicted

Q.

Assertion: All the collisions of the reactant molecules lead to product formation.

Reason: Only those collisions in which the molecules have the correct orientation and sufficient kinetic energy lead to compound formation.

1. Both assertion and reason are incorrect.

2. Assertion is incorrect but reason is correct.

3. Both assertion and reason are correct and the reason is correct explanation of assertion.

4. Assertion is correct but reason is incorrect.

5. Both assertion and reason are correct but reason does not explain assertion.

Q. Which of the following arrangement of bond dissociation enthalpy of halogens is correct?

1. $F-F>Cl-Cl>Br-Br$
2. $F-F<Cl-Cl>Br-Br$
3. $F-F<Cl-Cl<Br-Br$
4. $F-F>Cl-Cl<Br-Br$

Q.

STATEMENT-1 : $H_2{O}_2$ has higher boiling point than water.
STATEMENT-2 : $H_2{O}_2$ has stronger hydrogen bonding interactions than that shown by water.

1. STATEMENT-1 is True, STATEMENT-2 is True; STATEMENT-2 is a correct explanation for STATEMENT-1
2. STATEMENT-1 is True, STATEMENT-2 is True; STATEMENT-2 is NOT a correct explanation for STATEMENT-1
3. STATEMENT-1 is True, STATEMENT-2 is False
4. STATEMENT-1 is False, STATEMENT-2 is True

Q. What are the oxidation state of Cu and Fe in CuFeS2 ?

Q. Bond energy of ${Cl}_2,{Br}_2$ and $I_2$ follow the order :

1. ${Cl}_2>{Br}_2>I_2$
2. ${Br}_2>{Cl}_2>I_2$
3. $I_2>{Br}_2>{Cl}_2$
4. $I_2>{Cl}_2>{Br}_2$

Q. Ge(II) compounds are powerful reducing agents whereas Pb(IV) compounds are strong oxidants, because

1. $\text{Pb is more electropositive than Ge}$
2. $\text{Ionization potential of lead is less than that of Ge}$
3. $\text{Ionic radii of}P{b}^{2+}\text{and}P{b}^{4+}\text{are larger than those of}G{e}^{2+}\text{and}G{e}^{4+}$
4. $G{e}^{4+}\text{is more stable than}G{e}^{2+}\text{whereas}P{b}^{2+}\text{is more stable than}P{b}^{4+}$

Q.

In which of the following oxidation states La achieve the noble gas configuration?

1. +2

2. +7

3. +3

4. +5

Q. Assertion :$H_2$ molecule is more stable than $He-H$ molecule. Reason: The antibonding electron in $He-H$ molecule decreases the bond order and there by stability.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Q.

1. True
2. False

Q. As the oxidation number of a transition metal in transition metal oxide increases, the melting point

1. Increases
2. Decreases
3. Remains the same
4. Cannot be predicted

Q. Which of the following does not exhibit inert pair effect?

1. Bi
2. Pb
3. B
4. Tl

Q.

Which M--M bond has highest bond energy -

1. Ge - Ge

2. Si - Si

3. Pb - Pb

4. Sn - Sn

Q. Which is correct order for bond energy?

1. $N_2>HF>O_2>H_2$
2. $N_2>O_2>HF>H_2$
3. $N_2>H_2>O_2>HF$
4. $HF>N_2>O_2>H_2$

Q. Which of the following arrangement of bond dissociation enthalpy of halogens is correct?
[1 Mark]

1. $F-F>Cl-Cl>Br-Br$
2. $F-F<Cl-Cl<Br-Br$
3. $F-F>Cl-Cl<Br-Br$
4. $F-F<Br-Br<Cl-Cl$

Q. When bond order increases, bond length decreases.

1. True
2. False

Q. Solve this:

12. In the lanthanoid series ( $Ce\to 58toLu\to 71$)

i) Which elements, compound acts as oxidising agent ?

ii) Which element show + 2 oxidation state (name any one) ?

iii) Which element has largest atomic radii ?

Q. The boiling point of $ICl$ is about ${40}^{\circ }C$ higher than $B{r}_2$. This might be because :

1. $I-Cl$ bond is stronger than $Br-Br$ bond
2. $I.E.$ of $I<I.E.$ of $Br$
3. the size of $I>Br$
4. $I-Cl$ is polar whereas $B{r}_2$ is non-polar

Q. Give reasons for the decrease in stability of +6 oxidation state and increase in +4 oxidation state of group 16 elements.

Q.

Which of the following elements has greater tendency to show +2 oxidation state ?

1. Lead

2. Carbon

3. Silicon

4. Germanium