1
JEE Main 2016 (Online) 10th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Extraction of copper by smelting uses silica as an additive to remove :
A
Cu2S
B
FeO
C
FeS
D
Cu2O
2
JEE Main 2016 (Online) 10th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Sodium extract is heated with concentrated HNO3 before testing for halogens because :
A
Silver halides are totally insoluble in nitric acid.
B
Ag2S and AgCN are soluble in acidic medium.
C
S2 and CN, if present, are decomposed by conc. HNO3 and hence do not interfere in the test.
D
Ag reacts faster with halides in acidic medium.
3
JEE Main 2016 (Offline)
MCQ (Single Correct Answer)
+4
-1
Change Language
Which one of the following ores is best concentrated by froth floatation method?
A
Siderite
B
Galena
C
Malachite
D
Magnetite
4
JEE Main 2015 (Offline)
MCQ (Single Correct Answer)
+4
-1
Change Language
In the context of the Hall-Heroult process for the extraction of Al, which of the following statements is false?
A
Al2O3 is mixed with CaF2 which lowers the melting point of the mixture and brings conductivity
B
Al3+ is reduced at the cathode to form Al
C
Na3AlF6 serves as the electrolyte
D
CO and CO2 are produced in this process
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