CBSE Questions for Class 11 Medical Chemistry Equilibrium Quiz 4 - MCQExams.com

A saturated salt water solution was heated and allowed to cool without adding any more salt in it.
Which of the following will take place?
  • Some salt appears to settle at the bottom.
  • Some more salt can be dissolved now.
  • No change takes place.
  • Both $$A$$ or $$B$$
Ionic solutions are good conductors of Electricity.
  • True
  • False
Dilute sulphuric acid splits into:
  • oxygen ions and hydrogen ions.
  • oxygen ions, hydrogen ions and sulphur ions.
  • hydrogen ions, oxygen ions and sulphate ions.
  • hydrogen ions and sulphate ions.
Solubility of $$AgCN$$ is maximum in :
  • acidic buffer solution
  • basic buffer solution
  • in pure water
  • equal in all solution
Available chlorine is liberated from bleaching powder when it :
  • is heated
  • reacts with acid
  • reacts with $${H_2 O}$$
  • reacts with $${CO_2}$$
In water, or aqueous solutions of $$ HCl$$ or $$ H_{2}SO_{4},$$ proton exists as:
  • $$H_{3}O^{+}$$
  • $$H(H_{2}O)_{4}^{+}$$
  • $$H(H_{2}O)_{n}^{+}$$
  • $$all\ correct$$
A $$0.10\space M$$ solution of $$HF$$ is $$8.0\mbox{%}$$ ionized. What is the $$K_a$$?
  • $$6.4\times10^{-4}$$
  • $$8.8\times10^{-4}$$
  • $$6.95\times10^{-4}$$
  • $$7.6\times10^{-4}$$
Chloride which is insoluble in water is :
  • sodium chloride
  • potassium chloride
  • mercurous chloride
  • calcium chloride
$$pH$$ of following solution is not affected by dilution:
  • $$0.01\ M\ CH_{3}COONH_{4}$$
  • $$0.01\ M\ NaH_{2}PO_{4}$$
  • $$0.01\ M\ NaHCO_{3}$$
  • All of these
Does $$Mg(OH)_2$$ react with sodium hydroxide?
  • True
  • False
Fear or excitement generally causes one to breathe rapidly and it results in the decrease of concentration of $${CO}_{2}$$ in blood. In what way, it will change the $$pH$$ of blood?
  • $$pH$$ will increase
  • $$pH$$ will decrease
  • No change
  • $$pH$$ will be $$7$$
At $${90}^{o}C$$ pure water has $$[{H}_{3}{O}^{+}]={10}^{-6}$$ $$mol/litre$$. The value of $${K}_{w}$$ at $${90}^{o}C$$ is
  • $${10}^{-6}$$
  • $${10}^{-12}$$
  • $${10}^{-8}$$
  • $${10}^{-14}$$
Calcium phosphate is present in tooth enamel, its nature is:
  • basic
  • acidic
  • neutral
  • none of the above
Addition of large quantity of Iron salt will coagulate blood.
  • True
  • False
Which of the following is acidic in nature? 
  • Lime juice
  • Human blood
  • Lime water
  • Antacid
If a salt of weak acid or base is added to a solution of its acid or base respectively, the:
  • dissociation of acid or base is diminished
  • the $$pH$$ of the solution in case of acid increases and in case of base decreases
  • mixing of two leads for precipitation
  • none of the above
To protect tooth decay we are advised to brush our teeth regularly. The nature of the tooth paste commonly used is:
  • acidic
  • neutral
  • basic
  • corrosive
$$NaCl + H_2SO_4\overset{\Delta}{\longrightarrow}HCl \ +$$
  • $$NaHSO_4$$
  • $$Na_2SO4$$
  • $$Na_2SO_3$$
  • none of the above
In the dissociation of $$NH_4OH$$, if excess if $$NH_4Cl$$ is added before adding $$NH_4OH$$, the concentration of:
  • $$NH_4^+$$ ions increases and $$OH^-$$ ions decreases
  • both $$NH_4^+$$ ions and $$OH^-$$ ions increases
  • $$NH_4^+$$ ions decreases and $$OH^-$$ ions increases
  • both $$NH_4^+$$ ions and $$OH^-$$ ions decreases
Assertion: Due to common ion effect, the solubility of $$HgI_2$$ is expected to be less in an aqueous solution of KI than in water. But $$HgI_2$$ dissolves in an aqueous solution of KI to form a clear solution.
Reason: $$I^{\circleddash}$$ ion is highly polarisable.
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Assertion is incorrect but Reason is correct
  • Both Assertion and Reason are incorrect
Acids do not show acidic behaviour in:
  • water
  • absence of water
  • basic solution
  • none of these
Assertion: On addition of $$NH_4Cl$$ to $$NH_4OH, pH$$ decreases but remains greater than 7.
Reason: Addition of $$\overset{\circleddash}{N}H_4$$ ion decreases ionisation of $$NH_4$$, thus [OH] decreases and also pH decreases.
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Assertion is incorrect but Reason is correct
  • Both Assertion and Reason are incorrect
Assertion: $$pH$$ value of $$HCN$$ solution decreases when $$NaCN$$ is added to it
Reason: $$NaCN$$ provides a common ion $$CN^{\circleddash}$$ to $$HCN$$
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
  • Assertion is correct but Reason is incorrect
  • Assertion is incorrect but Reason is correct
  • Both Assertion and Reason are incorrect
A farmer treats the soil of his field with lime when the soil has:
  • acidic nature
  • basic nature
  • neutral nature
  • None of the above
Which of the following reagents will give white precipitate with the aqueous solution of sulphurous acid?
  • $$BaCI_2$$
  • $$HCl$$
  • $$NaCl$$
  • $$KCl$$
Which of the following will supress the ionisation of acetic acid in aqueous solution?
  • $$NaCl$$
  • $$HCI$$
  • $$KCI$$
  • Unpredicatble
In the third group of qualitative analysis, the precipatitating reagent is $$NH_4Cl / NH_4OH$$. The function of $$NH_4Cl$$ is to 
  • increase the ionisation of $$NH_4OH$$
  • supress the ionisation of $$NH_4OH$$
  • convert the ions of group third into their respective chlorides
  • stabilise the hydroxides of group $$III$$ cations
Which of the following statements(s) is(are) correct?
  • The pH of $$1.0 \times 10^{-8} M$$ solution of HCI is 8
  • The conjugate base of $$H_2PO_4^{\circleddash}$$ is $$HPO_4^{2-}$$
  • Autoprotolysis constant of water increases with temperature
  • When a solution of weak monoprotic acid is titrated against a strong base, at half-neutralisation, point $$pH = (1/2) pK_a$$
The solubility of $$AgI$$ in $$NaI$$ solutions is less than that in pure water because:
  • $$AgI$$ forms complex with $$NaI$$
  • of common ion effect
  • solubility product of $$AgI$$ is less than that of $$NaI$$
  • the temperature of the solution decreases
Aqueous solutions of $$HNO_3, CH_3COOH$$ and $$CH_3COOK$$ of identical concentrations are given. The pair(s) of the solution which may form a buffer upon mixing is(are):
  • $$NaOH$$ and $$CH_3COOH$$
  • $$HNO_3$$ and $$CH_3COOK$$
  • $$CH_3COOH$$ and $$CH_3COOK$$
  • $$HNO_3+ CH_3COOH$$
$$H_3PO_4 \rightleftharpoons H^{\oplus}+H_2PO_4^{\circleddash};     K_{a_{1}} :$$
$$H_3PO_4^{\circleddash} \rightleftharpoons H^{\oplus}+HPO_4^{2-};     K_{a_{2}}:$$
$$HPO_4^{2-} \rightleftharpoons H^{\oplus}+PO_4^{3-};     K_{a_{3}}:$$
Mark out the incorrect statements
  • $$K_{a_{1}} > K_{a_{2}} > K_{a_{3}}$$
  • $$pH(H_2PO_4^{\circleddash})=\displaystyle \frac{pK_{a_1}+pK_{a_2}}{2}$$
  • Both $$H_3PO_4$$ and $$H_2PO_4^{\circleddash}$$ are more acidic than $$HPO_4^{2-}$$
  • Only $$HPO_4^{2-}$$ is amphiprotic anion in the solution
The $$pH$$ of a dilute solution of acetic acid was found to be $$4.3$$ The addition of a small crystal of sodium acetate will cause $$pH$$ to:
  • become less than $$4.3$$
  • become more than $$4.3$$
  • remain equal to $$4.3$$
  • unpredictable
A buffer solution can be prepared from a mixture of
  • Sodium acetate and acetic acid in water
  • Sodium acetate and hydrochloric acid in wafer
  • Ammonia and ammonium chloride in water.
  • Ammonia and sodium hydroxide in water
$$pOH$$ of water is $$7.0$$ at $$298 K$$. If water is heated to $$350 K$$, which of the following should be true? 
  • $$pOH$$ will decrease
  • $$pOH$$ will increase
  • $$pOH$$ will remain seven
  • Concentration of $$H^{\oplus}$$ ions will increae but that of $$\overset{\circleddash}{O}H$$ will decrease.
At $$55^0 C$$, autoprotolysis constant of water is $$4 \times {10}^{-14}$$. If a given sample of water has a $$pH$$ of 6.9, then it is:
  • acidic
  • basic
  • neutral
  • explosive
$$pOH$$ of $${H}_{2}O$$ is $$7.0$$ at $$298\ K$$. If water is heated at $$350\ K$$, which of the following should be true?
  • $$pOH$$ will decrease
  • $$pOH$$ will increase
  • $$pOH$$ will remain $$7.0$$
  • Concentration of $${H}^{+}$$ ions will increase but that of $$O{H}^{-}$$ will decrease
Calculate : $${K}_{b}$$ for $$B{({OH}_{4})}^{-}$$ given $$ {K}_{a}(B{(OH)}_{3})=6\times {10}^{-10}$$
  • $$8.3\times {10}^{-6}$$
  • $$1.66\times {10}^{-5}$$
  • $$3.3\times {10}^{-5}$$
  • None of these
The solubility of $$Ca{ F }_{ 2 }  \left( { K }_{ sp } = 3.4 \times { 10 }^{ -11 } \right)$$ in $$0.1  M$$ solution of $$NaF$$ would be
  • $$3.4\times { 10 }^{ -12 }M$$
  • $$3.4\times { 10 }^{ -10 }M$$
  • $$3.4\times { 10 }^{ -9 }M$$
  • $$3.4\times { 10 }^{ -13 }M$$
Addition of $$HCl$$ will not suppress the ionization of:
  • acetic acid
  • benzoic acid
  • $${H}_{2}S$$
  • sulphuric acid
When solid $$KCl$$ is added to a saturated solution of $$AgCI$$ in $$H_2O$$
  • Nothing happens
  • Solubility of $$AgCl$$ decreases
  • Solubility of $$AgCl$$ increases
  • Solubility product of $$AgCl$$ increases
Buffer solutions can be prepared from mixtures of:
  • $$HCl$$ and $$NaCl$$
  • $$NaH_2PO_4$$ and $$Na_2HPO_4$$
  • $$CH_3COOH + NaCl$$
  • $$NH_3OH+NH_3$$
Which of the following expressions is/are not true?
  • $$\left[ { H }^{ + } \right] =\left[ O{ H }^{ - } \right] =\sqrt { { K }_{ w } }$$ for a neutral solution at all temperatures
  • $$\left[ { H }^{ + } \right] >\sqrt { { K }_{ w } } \& \left[ O{ H }^{ - } \right] <\sqrt { { K }_{ w } } $$ for an acidic solution
  • $$\left[ { H }^{ + } \right] <\sqrt { { K }_{ w } } \& \left[ O{ H }^{ - } \right] >\sqrt { { K }_{ w } } $$ for an alkaline solution
  • $$\left[ { H }^{ + } \right] =\left[ O{ H }^{ - } \right] ={ 10 }^{ -7 }M$$ for a neutral solution at all temperatures
At $$90^oC$$, pure water has $$[H_3O^{\oplus}]=10^{-6.7}\, mol\, L^{-1}$$. What is the value of $$K_w$$ at $$90^oC$$? 
  • $$10^{-6}$$
  • $$10^{-12}$$
  • $$10^{-13.4}$$
  • $$10^{-6.7}$$
Determine $$[{OH}^{-}]$$ of a $$0.050\ M$$ solution of ammonia to which has been added sufficient $${NH}_{4}Cl$$ to make the total $$[{NH}_{4}^{+}]$$ equal to $$0.100 M$$. $$[{K}_{b({NH}_{3})}=1.8\times {10}^{-5}]$$
  • $$[{OH}^{-}]=9.0\times {10}^{-6}$$
  • $$[{OH}^{-}]=9.0\times {10}^{-8}$$
  • $$[{OH}^{-}]=9.0\times {10}^{-2}$$
  • $$[{OH}^{-}]=9.0\times {10}^{-9}$$
The ionic product of water ______  if a few drops of acid or base are added to it.
  • increases
  • decreases
  • remains the same
  • can not predict
In aqueous solution, the hydronium ion is further hydrated to species like:
  • $${H_5 O_2^{+}}$$
  • $${H_7 O_3^{+}}$$
  • $${H_8 O_3^{+}}$$
  • $${H_9 O_4^{+}}$$
Assertion: A solution of sodium acetate and ammonium acetate can act as a buffer.
Reason: A buffer solution consists of a mixture of a weak acid and its conjugate base or vice versa.
  • Both Assertion and Reason are true and Reason is the correct explanation of Assertion
  • Both Assertion and Reason are true but Reason is not the correct explanation of Assertion
  • Assertion is true but Reason is false
  • Assertion is false but Reason is true
  • Both Assertion and Reason are false
Assertion: A buffer has a definite pH value which changes, on keeping it or on diluting it.
Reason: A buffer solution is a mixture consisting of a weak acid and its conjugate base or vice versa.
  • Both Assertion and Reason are true and Reason is the correct explanation of Assertion
  • Both Assertion and Reason are true but Reason is not the correct explanation of Assertion
  • Assertion is true but Reason is false
  • Assertion is false but Reason is true
Assertion: AgCl is less soluble in aqueous sodium chloride solution than in pure water.
Reason: AgCl dissociates completely and more rapidly than NaCl.
  • Both Assertion and Reason are true and Reason is the correct explanation of Assertion
  • Both Assertion and Reason are true but Reason is not the correct explanation of Assertion
  • Assertion is true but Reason is false
  • Assertion is false but Reason is true
  • Both Assertion and Reason are false
In the presence of a common ion (incapable of forming complex ion), the solubility of salt _______  in solution.
  • increases
  • decreases
  • remains the same
  • cannot predict
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