CBSE Class 10 Science Case Study Questions Acids Bases and Salts MCQs

Case/Passage – 1
Marble’s popularity began in ancient Rome and Greece, where white and off-white marble were used to construct a variety of structures, from hand-held sculptures to massive pillars and buildings.

Question: A student added 10g of calcium carbonate in a rigid container, secured it tightly and started to heat it. After some time, an increase in pressure was observed, the pressure reading was then noted at intervals of 5 mins and plotted against time, in a graph as shown below. During which time interval did maximum decomposition took place?

(a) 15-20 min
(b) 10-15 min
(c) 5-10 min
(d) 0-5 min   

Answer: C

Question: Marble statues are corroded or stained when they repeatedly come into contact with polluted rain water.Identify the main reason.

(a) decomposition of calcium carbonate to calcium oxide
(b) polluted water is basic in nature hence it reacts with calcium carbonate
(c) polluted water is acidic in nature hence it reacts with calciumcarbonate
(d) calcium carbonate dissolves in water to give calcium hydroxide. 

Answer: C

Question: Gas A, obtained above is a reactant for a very important biochemical process which occurs in the presence of sunlight. Identify the name of the process –
(a) Respiration
(b) Photosynthesis
(c) Transpiration
(d) Photolysis and buildings.   

Answer: B

Question: The substance not likely to contain CaCO₃ is
(a) Dolomite
(b) A marble statue
(c) Calcined gypsum
(d) Sea shells.

Answer: C

Question: Calcium oxide can be reduced to calcium, by heating with sodium metal. Which compound would act as an oxidizing agent in the above process?
(a) sodium
(b) sodium oxide
(c) calcium
(d) calcium oxide Frothing in Yamuna: 

Answer: D

Case/Passage – 2

The primary reason behind the formation of the toxic foam is high phosphate content in the wastewater because of detergents used in dyeing industries, dhobi ghats and households.Yamuna’s pollution level is so bad that parts of it have been labelled ‘dead’ as there is no oxygen in it for aquatic life to survive. 

Question: High content of phosphate ion in river Yamuna may lead to:
(a) decreased level of dissolved oxygen and increased growth of algae 
(b) decreased level of dissolved oxygen and no effect of growth of algae
(c) increased level of dissolved oxygen and increased growth of algae
(d) decreased level of dissolved oxygen and decreased growth of algae 

Answer: A

Question: Which of the following correctly represents the solutions in increasing order of their hydronium ion concentration?
(a) P > Q > R > S
(b) P > S > Q > R
(c) S < Q < R < P
(d) S < P < Q < R 

Answer: C

Question: Which of the following statements is correct for the water with detergents dissolved in it?
(a) low concentration of hydroxide ion (OH– )and high concentration of hydronium ion (H3^O+)
(b) high concentration of hydroxide ion (OH–)and low concentration of hydronium ion (H₃O+)
(c) high concentration of hydroxide ion (OH–) as well as hydronium ion (H₃O+)
(d) equal concentration of both hydroxide ion (OH–) and hydronium ion (H₃O+).
The table provides the pH value of four solutions P, Q, R and S

Answer: B

Question: Predict the pH value of the water of river Yamuna if the reason for froth is high content of detergents dissolved in it.
(a) 10-11
(b) 5-7
(c) 2-5
(d) 7   

Answer: A

Question: If a sample of water containing detergents is provided to you, which of the following methods will you adopt to neutralize it?
(a) Treating the water with baking soda
(b) Treating the water with vinegar
(c) Treating the water with caustic soda
(d) Treating the water with washing soda 

Answer: B

I. Bleaching powder is a pale yellowish powder. It is soluble in water but due to the presence of impurities, we never observe a clear solution. Its chemical formula is Ca(OCl2) with its chemical name as Calcium hypochlorite. Bleaching powder is also called calcium chlorohypochlorite because it is considered as a mixed salt of hydrochloric acid and hypochlorous acid.

Question: The compound lime water that is used in the manufacture of bleaching powder is
A. Clear solution of Ca(OH)_2.
B. Milky Suspension of Ca(OH)_2.
C. Clear solution of CaCl_2.
D. Clear solution of CaCO₃.

Answer: A

Question: One of the products obtained during the electrolysis of aqueous Sodium Chloride(brine) used in the preparation of Bleaching powder is.
A. Sodium metal at cathode
B. Hydrogen gas
C. Chlorine gas
D. Slaked lime.

Answer: C

Question: One of the following cannot be considered as the use of bleaching powder
A. It is an oxidising agent.
B. it is used for disinfecting water.
C. it bleaches cotton and linen in the textile industry.
D. it releases Oxygen gas on heating which can be used for aeration of water bodies.

Answer: D

II. Water of crystallisation is the fixed number of water molecules present in one formula unit of a salt. water(s) of crystallization or water(s) of hydration are water molecules that are present inside crystals. Water is often incorporated in the formation of crystals from aqueous solutions. A salt with associated water of crystallization is known as a hydrate.

Question: Which of the following salt does not contain water of crystallisation?
A. Blue Vitriol
B. Baking Soda
C. Washing Soda
D. Gypsum.

Answer: B

Question: The temperature at which Gypsum (CaSO4 . 2H2O) into Plaster of Paris(CaSO4.1/2 H2O
A. 373 K
B. 273 K
C. 374 K
D. 375 K

Answer: A

Question: The formula of Plaster of Paris is CaSO4. ½ H2O, it is to be noted that half water molecule is shown to be attached as water of crystallisation. This indicates that
A. Only half water molecule is present in Calcium Sulphate crystal
B. Two formula units of Calcium Sulphate share one molecule of water.
C. Two formula units of calcium Sulphate share two molecules of water
D. Two formula units of Calcium Sulphate share one and a half molecules of water.

Answer: B