Correct Answer:
(C)
NH3
The Lewis acids are lone pair acceptors. The Lewis bases are lone pair donors. Nitrogen in NH3 has 5 electrons in which 3 of them are involved in bonding. That leaves one lone pair. This lone pair is available for bonding. Therefore, NH3 is a Lewis base. AlCl3, BF3 and FeCl3 are Lewis acids.
Ques:
12
Consider the following statements:
Assertion (A) : To dilute sulphuric acid, acid is added to water and not water to acid.
Reason (R) : Specific heat of water is very high.
(A) and (R) are true, and (R) is the correct explanation of
(A).
Correct Answer:
(A)
and (R) are true, but (R) is not a correct explanation of
Ques:
13
Limewater is turned milky by:
Correct Answer:
(B)
CO2
Carbon dioxide (CO2) reacts with calcium hydroxide to produce a white precipitate of calcium carbonate. Limewater is a solution of calcium hydroxide. So, if carbon dioxide is passed through limewater, the limewater will turn milky or cloudy white.
Ca(OH)2 + CO2 → CaCO3 + H2O
Ques:
14
Soda water obtained by passing carbon dioxide in water is :
Correct Answer:
(C)
Acidic in nature
The carbon dioxide (CO2) gas dissolved in water can cause water to become acidic. The acidity of water from dissolved CO2 can be reduced by a base such as baking soda (Sodium bicarbonate). When carbon dioxide is dissolved in the water, it forms carbonic acid (H2CO3) by reacting with water (H2O) and remains in dissolved state at high pressure. So, the soda- water becomes acidic in nature.
Ques:
15
Which of the following acid do not contain oxygen –
Correct Answer:
(C)
Hydrochloric Acid
Hydrochloric Acid (HCl) does not contain oxygen, as it is a compound of hydrogen and chlorine.
Ques:
16
An unknown gas quickly dissolves in water. This gaseous aqueous solution turns red litmus into the blue. This gas produces white flame with hydrogen chloride.
This unknown gas is –
Correct Answer:
(C)
Ammonia
The aqueous solution of ammonia is basic due to forming of ammonium hydroxide which changes the colour of red litmus into blue. Ammonia produces a white flame when it reacts with hydrochloric acid.
Ques:
17
Match List-I with List-II and select the correct answer from the code given below the lists.
List-I List-II
Bleaching powder 1. Sodium bicarbonate
Baking soda 2. Sodium carbonate
Washing powder 3. Calcium oxychloride
Plaster of Paris 4. Calcium sulphate hemihydrate
Code :
A B C D
Correct Answer:
(C)
3 1 2 4
The correctly matched lists are as follows :
List-I List-II
Bleaching powder - Calcium oxychloride (CaOCl2 )
Baking soda - Sodium bicarbonate (NaHCO3 )
Washing powder - Sodium carbonate (Na2CO3 )
Plaster of Paris - Calcium sulphate hemihydrate (CaSO4 .½H2O)
Ques:
18
What is Neela thotha?
Correct Answer:
(A)
Copper Sulphate
Neela thotha (blue vitriol) is a compound of copper and sulphate. Its chemical formula is CuSO4.5H2O.
Ques:
19
The chemical used for destroying fungi in water tank is :
Correct Answer:
(D)
Copper Sulphate
Copper sulphate (blue vitriol or neela thotha) is used for destroying fungi in water tank. It is also used as a fungicide to protect field crops.
Ques:
20
Match the following lists by using codes given below. Select the correct answer?