Tag: formal charge

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Questions Related to formal charge

Multiple choice chemistry chemical bonding and structure formal charge basics of chemical bonding types of bonds

Effective charge on each oxygen is $-\frac{1}{4}$ in?

  1. $SO _{3}^{2-}$
  2. $SO _{3-}^{4}$
  3. $ClO _{3}^{-}$
  4. $ClO _{4}^{-}$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In the perchlorate ion (ClO4-), there are four equivalent oxygen atoms sharing a single negative charge delocalized over the entire ion, meaning the effective charge on each oxygen atom is -1/4. In sulfite (SO3 2-), the charge per oxygen is -2/3, and in chlorate (ClO3-), it is -1/3.

Multiple choice chemistry chemical bonding and structure formal charge basics of chemical bonding types of bonds

Among ${ KO } _{ 2 },{ AIO } _{ 2 }^{ - },{ BaO } _{ 2 }\ and\ { NO } _{ 2 }^{ + }$, unpaired electron is present in :

  1. ${ NO } _{ 2 }^{ + }\quad and\quad { BaO } _{ 2 }$
  2. ${ KO } _{ 2 }\quad and\quad AI{ O } _{ 2 }^{ - }$
  3. ${ KO } _{ 2 }$ only
  4. $Ba{ O } _{ 2 }$ only
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This can be done by counting number of valence electrons


$KO _2=1+2\times 6=17$-Odd number of electrons and hence unpaired.


$AlO^{2-} _2=3+2\times 6+1=14$-Even number of electrons and hence paired.

$BaO _2=2+2\times6=14$-Even number of electrons and hence paired.

$NO^{+} _{2}=5+2\times6 -1=16$-Even number of electrons and hence paired.

Hence option C is the correct answer.

Multiple choice chemistry chemical bonding and structure formal charge basics of chemical bonding types of bonds

Which has highest specific charge?

  1. $Na^{+}(mass\ no\ =23)$
  2. $Mg^{2+}(mass\ no\ =24)$
  3. $Al^{+3}(mass\ no\ =27)$
  4. $Si^{+4}(mass\ no\ =28)$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Specific charge in the ratio of charge of ion to its mass.

Specific charge $=\dfrac { e }{ M } $
For ${ Na }^{ + }=\dfrac { e }{ 23 } ,\quad $ for ${ Mg }^{ 2+ }=\dfrac { 2\times e }{ 24 } $
For ${ Al }^{ 3+ }=\dfrac { 3\times e }{ 27 } ,\quad $ for ${ Si }^{ 4+ }=\dfrac { 4\times e }{ 28 } $
In is in the following order,
${ Si }^{ 4+ }>{ Al }^{ 3+ }>{ Mg }^{ 2+ }>{ Na }^{ + }$

Multiple choice chemistry chemical bonding and structure formal charge basics of chemical bonding types of bonds

In bisulphate ion, the formal charge on sulphur atom is:

  1. $+1$
  2. $+2$
  3. $+4$
  4. $+6$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In the bisulphate ion (HSO4-), the sulphur atom is bonded to four oxygen atoms. One oxygen is bonded to hydrogen, and the others are double-bonded or single-bonded with negative charges to satisfy the octet rule, resulting in a formal charge of +2 on the central sulphur atom.

Multiple choice chemistry chemical bonding and structure formal charge basics of chemical bonding types of bonds

Formal charge on nitrogen and oxygen in $NO^- _3$ ion are respectively: 

  1. $0, \dfrac{-1}{3}$
  2. $+1, \dfrac{-1}{3}$
  3. $+1, \dfrac{-2}{3}$
  4. $0, \dfrac{-2}{3}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Formula change is basically a change given to an atom, on assuming that the electrons in a chemical bond are shared equally between the atoms, neglecting theirrelative, $EN.$

$FC=V-N-\cfrac{B}{2}$       $(V=\text{no. of valance electron}\N=\text{No. of non bonding electrons}\B=\text{No. of electrons in covalent bond})$
$FC$ on $N$ in $NO^- _3=0$
$FC$ on $O$ in $NO _3^-=\cfrac{-1}{3}$

Multiple choice chemistry chemical bonding and structure formal charge basics of chemical bonding types of bonds

Formal charge on nitrogen in $NO _{3}^{-}$ ion is

  1. $+1$
  2. $+2$
  3. $+5$
  4. $Zero$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the nitrate ion (NO3-), the nitrogen atom is at the center bonded to three oxygen atoms. Using the formal charge formula, nitrogen has 5 valence electrons, 0 lone pair electrons, and 8 bonding electrons (4 bonds), resulting in 5 - 0 - 4 = +1.

Multiple choice chemistry chemical bonding and structure formal charge basics of chemical bonding types of bonds

In the cyanide ion the formal negative charge is on:

  1. $C$
  2. $N$
  3. both $C$ and $N$
  4. resonate between $C$ and $N$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In the cyanide ion the formal negative charge resonates between $C$ and $N$. Cyanide ion has resonating structure, $-\overset { \ _ }{ C } \equiv N\longleftrightarrow \overset { \ _ }{ N } \underrightarrow { = } C$