CBSE Questions for Class 11 Medical Chemistry Equilibrium Quiz 6 - MCQExams.com

All  salts  are:
  • strong electrolytes
  • weak electrolytes
  • non electrolytes
  • either weak or strong electrolyte
When pH of rain water is less than 5.6, it is called:
  • monsoon rain
  • acid rain
  • basic rain
  • heavy rain
Tooth decay starts when the pH of the mouth is less than:
  • 4.5
  • 5.5
  • 6.5
  • 7.5
Why only $${As}^{+3}$$ gets precipitated as $${As}_{2}{S}_{3}$$ and not $${Zn}^{+2}$$ as $$ZnS$$ when $${H}_{2}S$$ is passed through an acidic solution containing $${As}^{+3}$$ and $${Zn}^{+2}$$?
  • Solubility product of $${As}_{2}{S}_{3}$$ is less than that of $$ZnS$$
  • Enough $${As}^{+3}$$ are present in acidic medium
  • Zinc salt does not ionise in acidic medium
  • Solubility product changes in presence of an acid
Match the following:
 Natural sourceAcid
Vinegara. Oxalic acid
Orangeb. Acetic acid
Tamarindc. Citric acid
Tomatod. Tartaric acid
  • 1-a, 2-b,3-d,4-c
  • 1-b, 2-c, 3-d, 4-a
  • 1-a, 2-c, 3-d, 4-a
  • 1-d, 2-a, 3-b, 4-c
The separation of $$H^{+}$$ ion from the _______ molecules cannot occur in the absence of water.
  • $$HCl$$
  • $$NaOH$$
  • $$H_{2}SO_{4}$$
  • none of the above
Match the following
Natural sourceAcid
1. Sour milk (Curd)a. Lactic acid
2. Lemonb. Citric acid
3. Ant stingc. Methanoic acid
  • 1-a, 2-b, 3-c
  • 1-a, 2-c, 3-b
  • 1-c, 2-b, 3-a
  • 1-b, 2-a, 3-c
Why does survival of aquatic life becomes difficult because of acid rain?
  • When acid rain falls into the river, it lowers the pH of the river water.
  • When acid rain falls into the river, it increases the pH of the river water.
  • Acid rain does not cause any change in the river water.
  • None of the above
Which part of the tooth, made up of a crystalline form of calcium phosphate, is the hardest substance in the body?
  • Root
  • Body
  • Enamel
  • All
0.1 M acetic acid gets 1% ionised. If it ionise 10 times, then concentration of $$ [H^+] $$ will be
  • 0.001
  • 0.01
  • 0.05
  • 0.1
At $$80^{\circ} C$$, distilled water $$(H_{3}O^{+})$$ has concentration equal to $$1\times 10^{-6}\ mol/ litre$$. The value of $$K_{w}$$ at this temperature will be:
  • $$1\times 10^{-6}$$
  • $$1\times 10^{-12}$$
  • $$1\times 10^{-9}$$
  • $$1\times 10^{-15}$$
Which of the following is a weak acid?
  • Acetic acid
  • Formic acid
  • Carbonic acid
  • All of the above

An acid is a compound which when dissolved in water yields:
  • hydroxide ions
  • hydronium ions
  • hydrogen
  • none of the above

$$HCl+H_2O \longrightarrow$$
  • $$H + Cl$$
  • $$HOCl + Cl^-$$
  • $$H_3O^+ + Cl^-$$
  • none of the above
What are strong acids and weak acids?
  • An acid which dissociates completely or almost completely in water are strong acids and an acid that dissociates only partially when dissolved in water are weak acids.
  • An acid which dissociates completely in water are strong acids and an acid which dissociates almost completely in water are weak acids.
  • An acid which do not dissociate completely in water are strong acids and an acid which dissociates almost completely in water are weak acids.
  • An acid that dissociates only partially when dissolved in water are strong acids and an acid which do not dissociate completely in water are weak acids.
Greater the number of hydronium ions present:
  • greater is the strength of acid
  • greater is the strength of base
  • lower is the strength of base
  • both $$A$$ and $$B$$
The strength of an acid depends on the concentration of the hydronium ions ________ present in a solution.
  • $$H^+$$
  • $$H_3O^+$$
  • $$OH^-$$
  • All of the above

$$NaOH+H_2O \longrightarrow$$
  • $$NaO+H_2$$
  • $$Na^+ + H^-$$
  • $$Na^+ +OH^-$$
  • none of the above
The product of molar concentrations of hydrogen ions and hydroxide ions in a $$0.01   M$$ aqueous solution of sodium chloride is known as
  • Hydrolysis constant of salt
  • Dissociation constant of acid
  • Dissociation constant of base
  • Ionic product of water
A salt is a general name given to the chemical produced during _______ reaction between an acid and a base
  • decomposition
  • neutralization
  • displacement
  • double decomposition

The properties of alkalis are due to the presence of ________ ions.
  • positive
  • negative
  • hydroxyl
  • both $$B$$ and $$C$$
The decreasing acidic strength of a few of the acids $$HCOOH, {CH}_{3}COOH, {C}_{2}{H}_{5}COOH$$ and $${C}_{3}{H}_{7}COOH$$ is due to
  • increase in $$+I$$ effect due to alkyl group
  • increase in $$-I$$ effect due to alkyl group
  • decrease in $$+I$$ effect due go alkyl group
  • increase in $$+M$$ effect
A $$0.1\ M$$ aqueous solution of a weak acid is $$2\%$$ ionized. If the ionic product of water is $$1\times 10^{-14}$$, the $$[OH^-]$$ is:
  • $$5\times 10^{-12}$$M
  • $$2\times 10^{-3}$$M
  • $$1\times 0^{-14}$$M
  • none of these
In III group precipitation, $$NH_4Cl$$ is added before adding $$NH_4OH$$ to.
  • Decrease conc. of $$OH^-$$
  • Prevent interference of $$PO^{3-}_4$$
  • Increase conc. of $$Cl^-$$
  • Increase conc. of $$OH^-$$ ion.
In acid rain, pH of rain water is:
  • 7
  • 9.0
  • more than 9.6
  • below 5.6
Which buffer solution comprising of the following has its $$pH$$ value greater than 7?
  • $${ CH }_{ 3 }COOH$$+$${ CH }_{ 3 }COONa$$
  • $$HCOOH + HCOOK$$
  • $${ CH }_{ 3 }COO{ NH }_{ 4 }$$
  • $${ NH }_{ 4 }OH+{ NH }_{ 4 }Cl$$
Which is a general process in which molecules separate or split into smaller particles?
  • Association
  • Ionisation
  • Dissociation
  • Recombination
If the dissociation constants of two substances are $${K}_{1}$$ and $${K}_{2}$$ respectively, then the ratio of degree of dissociation for a given concentration, is given by
  • $$\cfrac{{K}_{1}}{{K}_{2}}$$
  • $$\sqrt{\cfrac{{K}_{1}}{{K}_{2}}}$$
  • $$\cfrac { { \left( { K }_{ 1 } \right) }^{ 2 } }{ { K }_{ 2 } } $$
  • $$\cfrac { { K }_{ 1 }.{ K }_{ 2 } }{ { K }_{ 2 } } $$
When an acid dissolves in water, it gives:
  • proton
  • negative ion
  • hydroxide ion
  • both $$A$$ and $$B$$
$$H_2SO_4 +  H_2O \rightarrow$$

The product of the reaction is:
  • $$H^{+} + HSO_4{^-}$$
  • $$H_3O^{+} + {HSO_4}^{-}$$
  • $$H_3O^{+} + SO_4^{-2}$$
  • None of the above
Why does $$HCl$$ ionize in solution if they are covalently bonded?
  • Many bonds can be covalent in one situation and ionic in another
  • It does not ionize
  • They are not covalently bonded
  • None of the above
Which bond is broken when an acid dissolves in water?
  • Covalent
  • Recombination bond
  • Ionic
  • All of the above
The $$pH$$ of boiling water is $$6.4$$. This implies that boiling water is:
  • slightly basic
  • slightly acidic
  • neutral
  • amphoteric
Protons ( $$H^+$$ ions ) are found when a substance is dissolved in water. The substance is ___________.
  • $$KOH$$
  • $$NaH$$
  • $$H_{2}SO_{4}$$
  • $$NH_{3}$$
  • $$CH_{4}$$
Why $$HF$$ is a weak acid while $$HCl$$ is a strong acid?
  • $$HF$$ produces very few $$H^{+}$$ ions in water
  • $$HCl$$ dissociates completely to produce many $$H^{+}$$ ions in water
  • Both $$A$$ and $$ B$$
  • None of the above
$$H_3O^{+}$$ is a:
  • hydrated negative ion
  • negative ion
  • dehydrated proton
  • hydrated proton
Which of the following is a strong acid?
  • $$CH_3COOH$$
  • $$HNO_3$$
  • $$H_2CO_3$$
  • All of the above
Mixing a concentrated acid with water reduces the concentration of:
  • hydronium ions
  • hydrogen atoms
  • oxygen atom
  • none of the above
In order to make a buffer solution, a weak monoprotic acid could be added to :
  • another acid
  • another base
  • its conjugate base
  • its conjugate acid
  • a strong base
What is the common ion effect?
  • When the addition of an ion common to two solutes causes precipitation or reduces ionization.
  • When a molecule is added to a solution and causes precipitation or reduces ionization
  • When the subtraction of an ion common to two solutes causes precipitation or reduces ionization.
  • The effect of adding ions to a solution.
  • When any ion is added to a solution and causes precipitation or reduces ionization.
A buffer solution:
  • rapidly changes pH due to addition of an acid.
  • resists changes in pH.
  • does not change pH at all.
  • changes pH only with the addition of a strong base.
Which of the following pairs of species could be a buffer?
  • H$$^+$$ and Cl$$^-$$
  • H$$_2$$CO$$_3$$ and HCO$$_3^-$$
  • Na$$^+$$ and NO$$_3^-$$
  • Na$$^+$$ and OH$$^-$$
  • HNO$$_3$$ and NO$$_3^-$$
Which of the following statements are correct about dissociation?
  • Dissociation generally refers to breaking a compound into smaller pieces, usually reversibly.
  • Dissociation can happen without the formation of charged species
  • Both $$A$$ and $$B$$
  • None of these
For the preparation of saturated $$PbS{ O }_{ 4 }$$ solution of 1 litre at 25 degrees, the minimum number of moles of $$PbS{ O }_{ 4 }$$ that must be added ($${ K }_{ sp }$$ at $$25$$ for $$PbS{ O }_{ 4 }=1\times { 10 }^{ -8 }$$) is :
  • $$1\times { 10 }^{ -16 }mol$$
  • $$1\times { 10 }^{ -8 }mol$$
  • $$1\times { 10 }^{ -4 }mol$$
  • $$1\times { 10 }^{ -2 }mol$$
  • $$1\times { 10 }^{ -1 }mol$$
Which of the following is a correct statement?
  • The number of positive ions in solution equals the number of negative ions.
  • The total positive charge and total negative charge are equal in the solution.
  • The positive ions are known as cathodes.
  • The positive ions are known as anions.
  • None of the above
A beaker contains a saturated solution of copper(I) chloride. Copper(I) chloride is slightly soluble salt with a solubility product of $$1.2 \times 10^{−6}$$.
Which of the following salts when added to the solution would precipitate copper(I) chloride?
  • Sodium chloride
  • Potassium bromide
  • Silver(I) nitrate
  • Lead(II) acetate
  • Magnesium iodide
What is the relationship between $$[OH^-]$$ and $$[H_3O^+]$$ in a water solution?
  • When multiplied together, they equal a constant, $$K_w$$.
  • When multiplied together, they equal each other.
  • When divided, they equal a constant, $$K_w$$.
  • When one increases, the other increases.
  • They explain the acidity of a solution.
What is a buffer?
  • A solution that contains equal amounts of a weak acid and its conjugate base, or a weak base and its conjugate acid.
  • A solution that contains both a strong acid and a base.
  • A solution that contains an acid.
  • A solution that contains equal amounts of a strong acid and its conjugate base, or a strong base and its conjugate acid.
  • A solution that contains a base.
Which among the following resists a rapid change of pH?
  • Buffer
  • Indicator
  • Arrhenius acid
  • Arrhenius base
  • Neutral condition
Addition of water to $$X$$ solution will not change concentration of $$H_{3}O^{+}$$. $$X$$ is:
  • chemical pH indicator
  • acid/base buffer
  • anhydrous solution
  • hypotonic solution
  • supersaturated solution
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