Question Set A

cbse 10th Standard Science Acids, Bases and Salts Important Questions And Answers Study Material - QB365

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Questions:

Multiple Choice Question

20 x 1 = 20

Which of the following metals, do not corrode in moist air?

(a)

Copper

(b)

Iron

(c)

Gold

(d)

Silver

An element 'X' reacts with O₂ to give a compound with a high melting point. This compound is also soluble in water. The element 'X' is likely to be

(a)

iron

(b)

calcium

(c)

carbon

(d)

silicon

Baking soda is a mixture of

(a)

sodium carbonate and acetic acid

(b)

sodium carbonate and tartaric acid

(c)

sodium hydrogen carbonate and tartaric acid

(d)

sodium hydrogen carbonate and acetic acid

An aqueous solution 'A' turns phenolphthalein solution pink. On addition of an aqueous solution 'B' to 'A', the pink colour disappears. The following statement is true for solutions 'A' and 'B'.

(a)

A is strongly basic and B is a weak base.

(b)

A is strongly acidic and B is a weak acid.

(c)

A has pH greater than 7 and B has pH less than 7.

(d)

A has pH less than 7 and B has pH greater than 7.

In the given experimental setup, it is observed that on passing the gas produced in the reaction in the solution 'X' the solution 'X' first turns milky and then colourless.

The option that justifies the above stated observation that 'X' is aqueous calcium hydroxide and

(a)

it turns milky due to carbon dioxide gas liberated in the reaction and after sometime it becomes colourless due to formation of calcium carbonate.

(b)

it turns milky due to formation of calcium carbonate and on passing excess of carbon dioxide it becomes colourless due to formation of calcium hydrogen carbonate which is soluble in water.

(c)

it turns milky due to passing of carbon dioxide through it turns colourless as on further passing carbon dioxide, sodium hydrogen carbonate is formed which is soluble in water.

(d)

the carbon dioxide liberated during the reaction turns lime water milky due to formation of calcium hydrogen carbonate and after some time it turns colourless due to formation of calcium carbonate which is soluble in water.

Select a pair of natural indicator from the following:

(a)

Litmus and methyl orange

(b)

Turmeric and litmus

(c)

Phenolphthalein and methyl orange

(d)

Methyl orange and turmeric

Arrange the following metals in the order of their decreasing reactivity: Fe, Cu, Mg, Ca, Zn,Ag

(a)

Ca > Zn > Mg > Cu > Ag > Fe

(b)

Ca > Zn > Cu > Mg > Ag > Fe

(c)

Ca > Mg > Zn > Fe > Cu > Ag

(d)

Ca > Mg > Fe > Zn > Cu > Ag

Magnesium dissolves in hot water to form

(a)

MgO

(b)

Mg(OH)₂

(c)

MgOH

(d)

MgO.Mg(OH)₂

Cu + 2Ag(NO₃)₂ \(\longrightarrow \) CU(NO₃)₂ + 2Ag
Pb + CU(NO₃)₂ \(\longrightarrow \) Pb(NO₃)₂ + Cu
Zn + Pb(NO₃)₂ \(\longrightarrow \) Zn(NO₃)₂ + Pb
The most reactive metal is

(a)

(b)

(c)

(d)

10.

The process of coating of Zn over Fe is known as

(a)

Cathodic protection

(b)

Metallurgy

(c)

Tinning

(d)

Galvanization

11.

Which of the following will not evolve CO₂ upon heating?

(a)

CaCO₃

(b)

MgCO₃

(c)

ZnCO₃

(d)

Na₂CO₃

12.

When iron fillings are heated in a stream of dry hydrogen chloride the compound formed is FeCl_x where X is

(a)

(b)

(c)

(d)

13.

The aqueous solution of which of the following salt will have higher OH^- ions?

(a)

NaCI

(b)

Na₂SO₄

(c)

CH₃COONa

(d)

None of these

14.

In which of the following pairs, both are acidic salts?

(a)

KCI, KNO₃

(b)

Na₂SO₄, K₂SO₄

(c)

CH₃COONa, K₂CO₃

(d)

CuSO₄, AgNO₃

15.

The role of quick lime in soda lime (mixture) is to

(a)

Absorb moisture present in soda lime

(b)

Increase the efficiency of soda lime

(c)

Increase the pH of soda lime

(d)

Take part in reaction with NaOH

16.

Which of the following salts has no water of crystallization?

(a)

Blue vitriol

(b)

Washing soda

(c)

Baking soda

(d)

Gypsum

17.

Generally, non-metals are not conductors of electricity. Which of the following is a good conductor of electricity?

(a)

Diamond

(b)

Graphite

(c)

Sulphur

(d)

Fullerene

18.

During electrolytic refining of zinc, it gets

(a)

Deposited on cathode

(b)

Deposited on anode

(c)

Deposited on cathode as well as anode

(d)

Remains in the solution

19.

Which of the following are present in a dilute aqueous solution of hydrochloric acid?

(a)

\(H_3O^++CH^-\)

(b)

\(H_3O^++OH^-\)

(c)

\(Cl^-+OH^-\)

(d)

unionised HCl

20.

Which of the following substance will not give carbon dioxide on treatment with dilute acid?

(a)

Marble

(b)

Limestone

(c)

Baking soda

(d)

Lime

Assertion and reason

10 x 1 = 10

21.

Assertion (A) It is advised that while diluting an acid one should add water to acid and not acid to water keeping the solution continuously stirred.
Reason (R) The process of dissolving an acid into water is highly exothermic.
(a) Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
(b) Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
(c) Assertion is true but Reason is false.
(d) Assertion is false but Reason is true.

22.

Assertion: Metals in general have very high melting and boiling points.
Reason: Metals have the strongest chemical bonds which are metallic in nature.
Codes
(a) Both A and R are true, and R is correct explanation of the assertion.
(b) Both A and R are true, but R is not the correct explanation of the assertion.
(c) A is true, but R is false.
(d) A is false, but R is true.

23.

Assertion: The arrangement of metals in order of decreasing reactivities is called reactivity series.
Reason: Metals at the top of series are very reactive and metals at the bottom are least reactive.
Codes
(a) Both A and R are true, and R is correct explanation of the assertion.
(b) Both A and R are true, but R is not the correct explanation of the assertion.
(c) A is true, but R is false.
(d) A is false, but R is true.

24.

Assertion: On reacting with water, calcium starts floating over water.
Reason: Calcium reacts with cold water at room temperature.
Codes
(a) Both A and R are true, and R is correct explanation of the assertion.
(b) Both A and R are true, but R is not the correct explanation of the assertion.
(c) A is true, but R is false.
(d) A is false, but R is true.

25.

Assertion: Phenolphthalein is an acid-base indicator.
Reason: Phenolphthalein gives different colours in acidic and basic medium.
Codes
(a) Both A and R are true, and R is correct explanation of the assertion.
(b) Both A and R are true, but R is not the correct explanation of the assertion.
(c) A is true, but R is false.
(d) A is false, but R is true.

26.

Assertion: Tooth decay starts when the pH of the mouth is lower than 5.5.
Reason: Enamel starts corroding below 5.5 pH
Codes
(a) Both A and R are true, and R is correct explanation of the assertion.
(b) Both A and R are true, but R is not the correct explanation of the assertion.
(c) A is true, but R is false.
(d) A is false, but R is true.

27.

Assertion: Salt of KNO₃ is formed by strong base and weak acid.
Reason: Salt of NH₄CI is formed by weak base and strong acid.
Codes
(a) Both A and R are true, and R is correct explanation of the assertion.
(b) Both A and R are true, but R is not the correct explanation of the assertion.
(c) A is true, but R is false.
(d) A is false, but R is true.

28.

Assertion: Sodium carbonate pentahydrate is also known as washing soda.
Reason: Chief raw materials for the manufacture of washing soda are NH₃,NaCI and CaCO_3.
Codes
(a) Both A and R are true, and R is correct explanation of the assertion.
(b) Both A and R are true, but R is not the correct explanation of the assertion.
(c) A is true, but R is false.
(d) A is false, but R is true.

29.

Assertion: Lead is less reactive than copper.
Reason: Copper can displace zinc from its solution.
Codes
(a) If both assertion and reason are true and the reason is correct explanation of assertion.
(b) If both assertion and reason are true but reason is not a correct explanation of assertion.
(c) If assertion is true and reason is false.
(d) If both assertion and reason are false.

30.

Assertion: Hydrogen gas is evolved when a metal reacts with nitric acid.
Reason: All acids release hydrogen gas when reacted with metals.
Codes
(a) If both assertion and reason are true and the reason is correct explanation of assertion.
(b) If both assertion and reason are true but reason is not a correct explanation of assertion.
(c) If assertion is true and reason is false.
(d) If both assertion and reason are false.

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Answers Key:

Multiple Choice Question

20 x 1 = 20

(b)
calcium

(b)
it turns milky due to formation of calcium carbonate and on passing excess of carbon dioxide it becomes colourless due to formation of calcium hydrogen carbonate which is soluble in water.

(b)
Turmeric and litmus

(b)
Mg(OH)₂

(d)
Zn

10.

(d)
Galvanization

11.

(d)
Na₂CO₃

12.

(b)
2

13.

14.

(d)
CuSO₄, AgNO₃

15.

(a)
Absorb moisture present in soda lime

16.

17.

(b)
Graphite

18.

(a)
Deposited on cathode

19.

(a)
\(H_3O^++CH^-\)

20.

(d)
Lime

Assertion and reason

10 x 1 = 10

21.

(a) Both Assertion and Reason are correct and Reason is the correct explanation of Assertion.

22.

(a) Both A and R are true, and R is correct explanation of the assertion.

23.

(b): Metals at the top of the series are very reactive and therefore, they do not occur free in nature. The metals at the bottom of the series are least reactive and therefore, they normally occur free in nature.

24.

(b):Calcium floats over water because the bubbles of hydrogen gas formed get stick to the surface of the water.

25.

(a): Phenolphthalein is a weak organic acid and may be represented as HPh.
\(\mathrm{HPh} \ \ \ \ \rightleftharpoons \mathrm{H}^{+}+ \ \ \ \ \ \ \ \mathrm{Ph}^{-}\)
(Colourless) (Colourless) (Pink)
In acidic medium, excess of H⁺ions are present and so equilibrium is towards left and hence solution is colourless. While in basic medium, OH^-ions combine with H⁺ ions to form unionised water molecules and so equilibrium is towards right and hence solution has pink colour. Therefore, phenolphthalein is an acid-base indicator.

26.

(a) Both A and R are true, and R is correct explanation of the assertion.

27.

\(\text { (d): } \mathrm{KOH}+\mathrm{HNO}_{3} \longrightarrow \mathrm{KNO}_{3}+\mathrm{H}_{2} \mathrm{O}\)\(\mathrm{NH}_{4} \mathrm{OH}+\mathrm{HCl} \longrightarrow \mathrm{NH}_{4} \mathrm{Cl}\)
(Strong base) (Strong acid) (Weak base) (Strong acid)

28.

(d): Washing soda is sodium carbonate decahydrate, Na₂CO₃·10H₂O.

29.

(d) If both assertion and reason are false.

30.

(d) If both assertion and reason are false.(exceptional case is nitric acid)