Tag: p- block elements-ii

Questions Related to p- block elements-ii

Which of the following has seven valence electrons?

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. $Na^{+}$

  2. $Al$

  3. $F$

  4. $Ti$

  5. $B$

Show answer
Correct Option: C
Explanation:

We know that halogens have 7 electrons in their valence shell.

$F, Cl, Br, I$ are halogens.
Hence, option $C$ is correct.

Which of the following statement is wrong? In the reaction $2KCl{ O } _{ 3 }+{ I } _{ 2 }\rightarrow 2KI{ O } _{ 3 }+{ Cl } _{ 2 }$?

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. ${ Cl } _{ 2 }$ is more reactive than $I _{ 2 }$

  2. When $KCl{ O } _{ 3 }$ reacts with $I _{ 2 }$, ${ Cl } _{ 2 }$ is liberated

  3. $KCl{ O } _{ 3 }+{ I } _{ 2 }$ is a redox reaction and $I _{ 2 }$ is oxidized

  4. In the above reaction, $I _{ 2 }$ is reduced

Show answer
Correct Option: D
Explanation:

the given reaction is

${ 2KClO } _{ 3 }+{ I } _{ 2 }\rightarrow { 2KIO } _{ 3 }+{ Cl } _{ 2 }$
in reactant,oxidation state of iodine in ${ I } _{ 2 }=0$
in product,oxidation state of iodine in${ IO } _{ 3 }^{ - }\quad $is 3
so,oxidation state of iodine change from 0 to5,so it is oxidlsed.

For electron affinity of halogens which of the following is correct?

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. $Br>F$

  2. $F>Cl$

  3. $Br>Cl$

  4. $F>I$

Show answer
Correct Option: D
Explanation:

  • Electron Gain Enthalpy is the energy released when one mole of an electron is added to gaseous atoms of an element. 
  • The correct order of Electron gain enthalpy of Fluorine family is,
$Cl>F>Br>I$
The reason for this is that the size of the fluorine atom is very small. So when an electron is added in the fluorine atom it will suffer more electronegativity as all the electrons will be very close to each other and hence the electron gain enthalpy of chlorine is more negative than that of fluorine.

Chlorine has two naturally occuring isotopes $ _{ 17 }^{ 37 }{ Cl }$ and $ _{ 17 }^{ 35 }{ Cl }$ and average atomic mass of chlorine is $35.5$. The percentage of $ _{ 17 }^{ 37 }{ Cl }$ is:

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. 25%

  2. 75%

  3. 40%

  4. 60%

Show answer
Correct Option: A

Select the correct statement (s)

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. HCI and HF do not from free radical easily due to larger bond-energy

  2. HI with a minimum bond energy is every reactive and instead from ${{\text{I}} _{\text{2}}}\,\,\,$

  3. Both (a) and (b)

  4. None of the above

Show answer
Correct Option: C
Explanation:

Bond dissociation energy with hydrogen decreased down the group so HI is will be the most reactive . HI is more reative because the bond dissociation energy is low due to difference in size of hydrogen and iodine so it can be easily breaked.

Addition of halogen $(C{l _2} or B{r _2})$ to alkenes goes through formation of :

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. Carbocation

  2. Carbanion

  3. Cyclic halonium ion

  4. Carbon free radical

Show answer
Correct Option: C

In which of the following, oxidation number of chlorine is $ + 5 ?$

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. $Cl _{2}O _{7}$

  2. $\mathrm { ClO } _ { 3 } ^ { - }$

  3. $\mathrm { CHO } ^ { - }$

  4. $\mathrm { ClO } _ { 4 } ^ { - }$

Show answer
Correct Option: B
Explanation:

Oxidation number of $Cl _2O _7$:-

   $2x-14=0$
$x=7$

Oxidation number of ${ClO _3}^{-}$:-
$x-6=-1$
$x=5$
Oxidation number of $ClO^-$:-
$x-2=-1$
$x=1$
Oxidation number of ${ClO _4}^-$:-

$x-8=-1$
$x=7$
hence option B is correct.

Which of the following has highest chlorine content ?

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. Pyrene

  2. DDT

  3. Chloral

  4. Gammaxene

Show answer
Correct Option: A

Compare oxygen and flourine in Ionic radius$\quad O^{2-} , F^-$:

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. $\space O^{2-} = F^-$

  2. $\space O^{2-} < F^-$

  3. $\space O^{2-}> F^-$

  4. $\space O^{2-} \geq F^-$

Show answer
Correct Option: C
Explanation:

Among the elements of same period the ion with more number of electrons and less number of protons is having more radius.If the number of electrons are same the ion with less number of protons is having more radius.

Here $\quad O^{2-} $and $ F^-$ both are having same 10 electrons but oxygen is having 8 protons(which can atrract outer electrons with less force than florine) and florine is having 9 protons.So the ionic radius of $\space O^{2-}>  F^-$

Hence option C is correct.

Oxidation of hydrogen halide, HX affords a method for the industrial and laboratory preparation of the halogen, $X _2$, in the free state in respect of all of the following except :

chemistry p- block elements-ii group 17 elements - general properties group 17 elements group 17 elements - properties

  1. fluorine.

  2. chlorine.

  3. bromine.

  4. iodine.

Show answer
Correct Option: A
Explanation:

Due to higher electronegativity, HF doesn't follow such reaction and fluorine doesn't form.