Tag: acids, bases and salts

Questions Related to acids, bases and salts

The precipitate formed when NaOH reacts with zinc is :

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

  1. $Zn[OH] _{2}$

  2. ZnO

  3. $ZnH _{2}$

  4. $Na _{2}ZnO _{2}$

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Correct Option: D

The salt we use in our food is:

chemistry acids, bases and salts common salt some useful compounds in everyday life salts and their properties

  1. $NaCl$

  2. $CaCl _2$

  3. $KCl$

  4. $MgCl _2$

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Correct Option: A
Explanation:

Sodium chloride$(NaCl)$, also known as common salt is used in food. It is obtained by evaporation of sea water.

However other salts like $MgCl _2,CaCl _2,KCl$ are used in replacement therapy and given when their amount in the body goes down.
Hence, the correct answer is option (A).

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?

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

  1. $\approx 1\times { 10 }^{ -10 }$

  2. $\approx 1\times { 10 }^{ -9 }$

  3. $\approx 3.33\times { 10 }^{ -9 }$

  4. $\approx 3.33\times { 10 }^{ -10 }$

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Correct Option: A
Explanation:

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

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

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

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

  1. $1$ mole KOH

  2. $4$ mole KOH

  3. $2$ mole KOH

  4. $1$ mole Ca(OH)$ _2$

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Correct Option: B

Baking soda turns:

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

  1. turmeric to red

  2. purple-cabbage juice to green

  3. red litmus to blue

  4. all of the above

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Correct Option: D
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).

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

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

  1. acidic

  2. basic

  3. neutral

  4. all of these 

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Correct Option: B
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.

Which of the following equation represents action of alkali on aluminium oxide?

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

  1. $Al _2O _3+2NaOH\rightarrow2NaAlO _2+H _2O$

  2. $Al _2O _3+2KOH\rightarrow2KAlO _2+H _2O$

  3. $Al _2O _3+KOH\rightarrow KAlO _2+H _2O$

  4. Both A and B

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Correct Option: D
Explanation:

$Al _2O _3+KOH\rightarrow KAlO _2+H _2O$ 

Oxides and hydroxides of certain metals are ________ in nature.

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

  1. Acidic

  2. Amphoteric

  3. Basic

  4. Neutral

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Correct Option: B
Explanation:

Oxides and hydroxides of certain metals are amphoteric in nature.

Which of the following equation represents action of alkali on metal?

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

  1. $Zn+2NaOH\rightarrow Na _2ZnO _2+H _2$

  2. $Zn+2KOH\rightarrow K _2ZnO _2+H _2$

  3. $Pb+2KOH\rightarrow K _2PbO _2+H _2$

  4. All of the above

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Correct Option: D
Explanation:

Alkali reacts with hot concentrated caustic alkalies to give corresponding soluble salt and liberate hydrogen.

Which of the following equation is correct for action of alkali on aluminium?

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

  1. $2Al+2NaOH+2H _2O\rightarrow2NaAlO _2+3H _2$

  2. $2Al+2KOH+2H _2O\rightarrow2KAlO _2+3H _2$

  3. $Al+NaOH+H _2O\rightarrow NaAlO _2+H _2$

  4. Both A and B

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Correct Option: D
Explanation:

$2Al+2NaOH+2H _2O\rightarrow2NaAlO _2+3H _2$ and $2Al+2KOH+2H _2O\rightarrow2KAlO _2+3H _2$