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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, $-\overset { \ _ }{ C } \equiv N\longleftrightarrow \overset { \ _ }{ N } \underrightarrow { = } C$

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

A molecule with highest bond energy is:

  1. Fluorine

  2. Chlorine

  3. Bromine

  4. Iodine
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Bond dissociation energy in $KJ mol^-1$
$F _2-158$
$Cl _2-244$ 
$Br _2-93$ 
$I _2-151$ 
Hence, in order of decreasing bond strength: 
$Cl _2>Br _2>F _2>I _2$
Fluorine is an anomaly. 

Bond strength decreases from chlorine to iodine as down the group, the atomic size becomes larger and thus the valence electron orbitals become more diffused, causing the overlap of orbitals to become less effective. Therefore the halogen-halogen bond becomes weaker from chlorine to iodine.Fluorine is an exception due to its extremely small size. The F-F bond length is so short that the lone pairs of electrons on the fluorine atoms repel each other and weakens the F-F bond. 

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

In which of the following molecules partial charge separation does not take place?

  1. Chlorine

  2. Hydrochloric acid

  3. Water

  4. Ammonia
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cl molecules are covalent in nature so it is non polar molecule. Non polar compound consists of molecules linked through chemical bonds arranged in such a way that the distribution of charges are symmetrical. Non polar bonds do not exhibit polarity and do not form ions in their solution. These compounds do not dissolve in water which is a polar molecule.

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

The partial charge separation between the bonded atoms gives rise to ___________ in that compound.

  1. covalent character

  2. coordinate character

  3. ionic character

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Partial charge separation between the bonded atoms gives rise to ionic character in the molecule due to the electronegativity difference, a quite small degree of polarization occurs.

Multiple choice chemistry oxidation- reduction reactions redox reactions and electrode processes redox and electrode processes applications of redox reaction

The life span of a Daniel cell may increased by:

  1. large Cu electrode
  2. lowering of CuSO$ _{4}$ concentration
  3. lowering of ZnSO$ _{4}$ concentration

  4. large zinc electrode
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In a daniel cell at anode Zn gets converted to $Zn^{2+}$
$\therefore$ If the size of electrode is increases more zinc can be oxidized,
hence the life span of the cell may be increased

Hence, option d is correct.