Tag: chemical equilibrium and acids-bases

Questions Related to chemical equilibrium and acids-bases

Which of the following properties of a solution of $NaCl$ will not vary as the concentration of salt is increased?

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. $pH$

  2. Density

  3. Refractive index

  4. Electrical conductivity

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Correct Option: C
Explanation:

The presence of salts influences most physical properties of sea water (density, compressibility, freezing point, temperature of the density maximum) to some degree but does not determine them. Some properties (viscosity, light absorbtion,refractive index) are not significantly affected by salinity. (Particle and dissolved matter do affect light absorption in sea water and this influence is used in most optical applications.) Two properties which are determined by the amount of salt in the sea are conductivity and osmotic pressure.

If a salt after rubbing with fingers gives the smell of ammonia, then the salt is:

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. ammonium chloride

  2. sodium carbonate

  3. calcium carbonate

  4. lead sulphide

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Correct Option: A
Explanation:

If a salt after rubbing with fingers, gives the smell of ammonia, then the salt may be ammonium chloride.
After rubbing, due to warming, ammonium chloride may decompose to give ammonia and hydrogen chloride.
$\displaystyle NH _4Cl \xrightarrow {warm} NH _3 + HCl$

The phenomenon of crumbling to powder of sodium carbonate crystals on exposure to air is known as :

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. deliquescence

  2. isomorphism

  3. efflorescence

  4. none of the above

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Correct Option: C
Explanation:

The phenomenon of crumbling to a powder of sodium carbonate crystals on exposure to air is known as efflorescence.

Many salts absorb water from the atmosphere. This property is called :

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. hydration

  2. dehydration

  3. deliquescence

  4. efflorescence

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Correct Option: C
Explanation:

Deliquescent salts have strong affinity for moisture and become liquid by absorbing moisture from air. It is hygroscopic in nature e.g. calcium chloride, zinc chloride,magnesium chloride,sodium hydroxide.

Which one of the following substance will be most suitable for cutting a very hard material?

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. Silicon carbide

  2. Lead

  3. Zinc metal

  4. Sodium chloride crystal

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Correct Option: A
Explanation:
Silicon carbide is most suitable for cutting a very hard material.
In manufacturing processes it is used for its hardness in abrasive machining processes such as grinding, honing, water-jet cutting and sandblasting.

Which of the  following methods is not used for preparing a salt?

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. Reaction between an acid and a base

  2. Action of acid on metals

  3. Action of acid on metal oxides

  4. Dissolution of acids in water

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Correct Option: D
Explanation:

If acid is added to water the solution that forms is very dilute and small amount of heat is released so this reaction does not produce any salt.

Which of the following salt gets hydrolyzed in aqueous solution? A salt of :

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. weak acid and weak base

  2. strong acid and weak base

  3. weak acid and strong base

  4. all of the above

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Correct Option: D
Explanation:

Common kind of hydrolysis occurs when a salt of a weak acid or or weak base or both is dissolved in water. Water spontaneously ionizes into hydroxide anions and hydronium cations. The salt also dissociates into its constituent anions and cations.

Aqueous solution of sodium acetate is :

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. neutral

  2. weakly acidic

  3. strongly acidic

  4. alkaline

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Correct Option: D
Explanation:

Sodium acetate is the sodium salt of acetic acid. Acetic acid reacts with sodium carbonate or sodium hydroxide to form a basic solution of sodium acetate which acts as buffer with acetic acid.

Which of the following salt gets hydrolyzed in aqueous solution? 

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. A salt of weak acid and weak base

  2. A salt of strong acid and weak base

  3. A salt of weak acid and strong base

  4. All of the above

Show answer
Correct Option: D
Explanation:
Salts, when placed in water, will often react with the water to produce $H _{3}O^+$ or $OH^-$.This is known as a hydrolysis reaction.
A salt can be made of either a weak acid and strong base(i.e., basic salt), strong acid and weak base(i.e., acid salt), or a weak acid and weak base(i.e., either neutral, acidic or basic) gets hydrolyzed in aqueous solution.

A solution of sodium chloride will:

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. turn red litmus blue

  2. turn blue litmus red

  3. turn red litmus orange

  4. not change the colour of either red or blue litmus

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Correct Option: D
Explanation:

Litmus paper can be used as an indicator to know whether a given substance is acidic, basic or neutral in nature.

Acidic substances turn blue litmus paper red but they have no effect on the red litmus paper.
Basic substances turn red litmus paper blue but have no effect on the blue litmus paper.
On the other hand, neutral substances have no effect on the blue as well as the red litmus paper.
Hence, the correct answer is option (D).