Tag: chemistry

Questions Related to chemistry

Which of the following is least basic?

reactions of acids and bases properties of acids and bases acids, bases and salts acids and bases chemistry

  1. NF3N

  2. NH3

  3. NCl3

  4. NI3

Show answer
Correct Option: A

In which case of mixing a strong acid and a base each of $1$N concentration, temperature rise is highest?

reactions of acids and bases properties of acids and bases acids, bases and salts acids and bases chemistry

  1. $20$ ml, acid + $30$ ml alkali

  2. $10$ ml, acid + $40$ ml alkali

  3. $20$ ml, acid + $20$ ml alkali

  4. $30$ ml, acid + $20$ ml alkali

Show answer
Correct Option: C
Explanation:

More amount of acid reacts with equal amount of base, higher the amount of heat releases.

So, $20ml$ of acid+$20ml$ of alkali.

Conjugate base of ${ H } _{ 3 }{ PO } _{ 4 }$?

reactions of acids and bases properties of acids and bases acids, bases and salts acids and bases chemistry

  1. ${ H } _{ 2 }{ PO } _{ 4 }^{ - }$

  2. ${ H } _{ }{ PO } _{ 4 }^{ 2- }$

  3. ${ H } _{ 4 }{ PO } _{ 4 }^{ + }$

  4. ${ H } _{ 3 }{ PO } _{ 4 }^{ }$

Show answer
Correct Option: A
Explanation:

${H _2PO _4}^-$ is conjugate base of $H _3PO _4$  .

$H _2O _2$ is a:

reactions of acids and bases properties of acids and bases acids, bases and salts acids and bases chemistry

  1. monobasic acid

  2. dibasic acid

  3. neutral compound

  4. weal alkali

Show answer
Correct Option: B
Explanation:
A dibasic molecule has two replaceable hydrogen atoms. Since $H _2O _2$ has two replaceable hydrogen atoms, That's why it is a dibasic acid.

$H _2O _2\rightarrow HO _2^−+H^+$

$HO _2^−\rightarrow O _2^{−2}+H^+$


$\mathbf{Hence\ the\ correct\ answer\ is\ option\ (B)}$

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

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

  1. $SO _{3}^{2-}$

  2. $SO _{3-}^{4}$

  3. $ClO _{3}^{-}$

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

Show answer
Correct Option: C

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

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

  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

Show answer
Correct Option: C
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.

Which has highest specific charge?

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

  1. $Na^{+}(mass\ no\ =23)$

  2. $Mg^{2+}(mass\ no\ =24)$

  3. $Al^{+3}(mass\ no\ =27)$

  4. $Si^{+4}(mass\ no\ =28)$

Show answer
Correct Option: D
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,
${ Si }^{ 4+ }>{ Al }^{ 3+ }>{ Mg }^{ 2+ }>{ Na }^{ + }$

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

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

  1. $+1$

  2. $+2$

  3. $+4$

  4. $+6$

Show answer
Correct Option: B

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

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

  1. $0, \dfrac{-1}{3}$

  2. $+1, \dfrac{-1}{3}$

  3. $+1, \dfrac{-2}{3}$

  4. $0, \dfrac{-2}{3}$

Show answer
Correct Option: A
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 $NO _3^-=\cfrac{-1}{3}$

Which of the following given below is incorrect :

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

  1. ONF is isoelectronic with ${O _2}{N^ - }$

  2. ${\rm{O}}{{\rm{F}} _2}$ is an oxide of fluorine

  3. $C{l _2}{O _7}$ is an anhydride of perchloric acid

  4. ${O _3}$ molecule is bent

Show answer
Correct Option: A