Tag: reactions of acids and bases

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

The chloride salt of a certain weak monoacidic organic base is hydrolysed to an extent of $3$% in its $0.1M$ solution at ${25}^{o}C$. Given that the ionic product of water is ${10}^{-14}$ at this temperature, what is the dissociation constant of the base?

  1. $\approx 1\times { 10 }^{ -10 }$
  2. $\approx 1\times { 10 }^{ -9 }$
  3. $\approx 3.33\times { 10 }^{ -9 }$
  4. $\approx 3.33\times { 10 }^{ -10 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

$h = 0.03$, $C = 0.1 M$ , $K _{w} = 10^{-14}$       

We know, $K _{a} = Ch^{2}   $
$\cfrac{K _{w}}{K _{b}} = Ch^{2}    \Rightarrow \cfrac{10^{-14}}{K _{b}} = (0.1)(0.03)^{2} \Rightarrow  \cfrac{10^{-9}}{9} \approx 1 \times 10^{-10}$

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

A mixture containing one mole of $BaCl _2$ and two moles of $H _2SO _4$ will be neutralized by:

  1. $1$ mole KOH
  2. $4$ mole KOH
  3. $2$ mole KOH
  4. $1$ mole Ca(OH)$ _2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

BaCl2 + H2SO4 -> BaSO4 + 2HCl. One mole of BaCl2 reacts with one mole of H2SO4 to produce 2 moles of HCl. The remaining 1 mole of H2SO4 is also acidic. Total acid to neutralize is 2 moles of HCl + 1 mole of H2SO4 (which has 2 H+), totaling 4 moles of H+. Therefore, 4 moles of KOH are required.

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

Baking soda turns:

  1. turmeric to red

  2. purple-cabbage juice to green

  3. red litmus to blue

  4. all of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Turmeric, purple cabbage juice (containing anthocyanin), and litmus paper all act as indicators which help us to detect whether a particular substance is acidic or basic.

In basic medium, turmeric changes it's colour to red, purple-cabbage juice turns to green and red litmus turns to blue.
Baking soda/Sodium carbonate $Na _2CO _3$ is basic in nature and thus causes the above changes in the indicators.
Hence, the correct answer is option (D).

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

China rose indicator is turned green by a certain solution. The solution is:

  1. acidic

  2. basic

  3. neutral

  4. all of these

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

An indicator is usually a weak acid or a weak base which changes colour in acidic or basic solutions.  The pigment anthocyanin present in the china rose flower makes its solution an indicator.
China rose solution gives dark pink colour with acid and green colour with base.