Tag: chemistry

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

Which of the following is least basic?

  1. <div class="question-option"><label></label><h2 class="question-option-name"><span class="MathJax"><span class="math"><span class="mrow"><span class="mi">N<span class="msubsup"><span class="mi">F<span class="mn">3<span class="MJX_Assistive_MathML">N</h2>

  2. <h2 class="question-option-name"><span class="MathJax"><span class="math"><span class="mrow"><span class="mi">N<span class="msubsup"><span class="mi">H<span class="mn">3</h2>

  3. <h2 class="question-option-name"><span class="MathJax"><span class="math"><span class="mi">N<span class="mi">C<span class="mrow"><span class="mi"><span class="msubsup"><span class="mi">l<span class="mn">3</h2>

  4. <h2 class="question-option-name"><span class="MathJax"><span class="math">N<span class="mrow"><span class="mi"><span class="msubsup"><span class="mi">I<span class="mn">3</h2>
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

NF3 is the least basic among the nitrogen trihalides because the highly electronegative fluorine atoms pull electron density away from the nitrogen atom, making the lone pair less available for donation.

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

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

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

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

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

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

$H _2O _2$ is a:

  1. monobasic acid

  2. dibasic acid

  3. neutral compound

  4. weal alkali
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

$H _2O _2\rightarrow HO _2^−+H^+$

$HO _2^−\rightarrow O _2^{−2}+H^+$


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

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 $NO _3^-=\cfrac{-1}{3}$