Tag: acids, bases and salts

Questions Related to acids, bases and salts

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

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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

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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.

$H _2O _2\rightarrow HO _2^−+H^+$

$HO _2^−\rightarrow O _2^{−2}+H^+$


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

Which of the following equation is the correct one?

action of alkalis on some metals and metal oxides analytical chemistry properties of acids and bases acids, bases and salts chemistry

  1. Amphoteric oxide / Hydroxide + acid$\rightarrow$ Salt + Hydrogen

  2. Amphoteric oxide / Hydroxide + alkali$\rightarrow$ Salt + Hydrogen

  3. Metal + alkali$\rightarrow$ Salt + Water

  4. Metal + alkali$\rightarrow$ Salt + Hydrogen

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Correct Option: D
Explanation:

Amphoteric oxide reacts with acid/alkali to produce salt and water not salt and hydrogen. Also, Metal and alkali react to give salt and liberate hydrogen not water. So, option D is correct.

Find the odd one with reasons [valency is not a criterion]: $Al(OH) _3, Pb(OH) _2, Mg(OH) _2, Zn(OH) _2$ :

action of alkalis on some metals and metal oxides analytical chemistry properties of acids and bases acids, bases and salts chemistry

  1. $Al(OH) _3$

  2. $Pb(OH) _2$

  3. $Mg(OH) _2$

  4. $Zn(OH) _2$

Show answer
Correct Option: C
Explanation:

$Mg(OH) _2$ is a basic hydoxide while rest are amphoteric hydroxides.

When aluminium hydroxide is reacted with excess sodium hydroxide, the soluble amphoteric compound is formed. Mark the correct formula. 

action of alkalis on some metals and metal oxides analytical chemistry properties of acids and bases acids, bases and salts chemistry

  1. $\displaystyle { \left[ { Al\left( OH \right) } _{ 4 } \right] }^{ - }$

  2. $\displaystyle { \left[ { Al\left( OH \right) } _{ 5 } \right] }^{ 2- }$

  3. $\displaystyle { \left[ { Al\left( OH \right) } _{ 6 } \right] }^{ 3- }$

  4. $\displaystyle { \left[ { Al\left( OH \right) } _{ 7 } \right] }^{ 4- }$

Show answer
Correct Option: A
Explanation:

$Al(OH) _3 + NaOH \rightarrow Na^+ [Al(OH) _4]^-$

 Aluminium hydroxide when reacted with excess sodium hydroxide, the soluble amphoteric compound  formed is sodium tetra hydroxoaluminate (III).

When aluminium hydroxide is reacted with excess ammonium hydroxide, the insoluble compound is formed. Mark the correct formula.

action of alkalis on some metals and metal oxides analytical chemistry properties of acids and bases acids, bases and salts chemistry

  1. $\displaystyle { \left[ { Al\left( OH \right) } _{ 4 } \right] }^{ 1- }$

  2. $\displaystyle { \left[ { Al\left( OH \right) } _{ 5 } \right] }^{ 2- }$

  3. $\displaystyle { \left[ { Al\left( OH \right) } _{ 6 } \right] }^{ 3- }$

  4. $\displaystyle { \left[ { Al\left( OH \right) } _{ 7 } \right] }^{ 4- }$

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Correct Option: C

If the pH of an alkali metal hydroxide is 13.6, the concentration of hydroxide is ;

action of alkalis on some metals and metal oxides analytical chemistry properties of acids and bases acids, bases and salts chemistry

  1. More than 1 M

  2. Between 0.1 M and 1 M

  3. Between 0.01 M and 1 M

  4. Less than 0.001 M

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Correct Option: B
Explanation:
Given that :

$pH = 13.6$

Thus, $pOH = 14 - 13.6$

                     $=0.4$
Hence,
$[O{H^ - }] = lo{g^{ - 1}}( - 0.4)$

               $ = 0.3979$

Therefore the value of $[O{H^ - }]$ is between $0.1M$ and $1M$.

Therefore, the option is B.

A salt contains two atoms of iron, three atoms of sulphur and twelve atoms of oxygen. Identify the corresponding acid and base from which it is formed.

action of alkalis on some metals and metal oxides analytical chemistry properties of acids and bases acids, bases and salts chemistry

  1. $H _2 SO _4, Fe (OH) _2$

  2. $H _2 SO _3, Fe (OH) _2$

  3. $H _2 SO _3, Fe (OH) _3$

  4. $H _2 SO _4, Fe (OH) _3$

Show answer
Correct Option: D
Explanation:

$Fe _{2}(SO _{4}) _{3}$ is the salt formed from $Fe(OH) _{3}$ and $H _{2}SO _{4}$. The balanced chemical equation can be written as:
$2Fe(OH) _{3} + 3H _{2}SO _{4} \rightarrow Fe _{2}(SO _{4}) _{3} +6H _{2}O$