The process of removing gangue from ores by using water and oil is:
A. Magnetic separation
B. Calcination
C. Froth flotation
D. Leaching
Answer: Option C
Solution (By JKExamLibrary)
Froth flotation separates sulfide ores: powdered ore mixed with water and pine oil; air bubbles carry oil-wetted ore particles to surface as froth; gangue sinks. Used for ZnS, PbS.
Explanation:
Covalent bonds are formed by the sharing of electrons, which typically occurs between two non-metal atoms that have high electronegativities and a tendency to gain electrons. Metals tend to lose electrons, forming ionic bonds with non-metals. Noble gases are generally inert and do not form bonds.
Explanation:
Graphite's layered structure with weak van der Waals forces between layers allows them to slide over each other, making it a good dry lubricant. It is used in machines where oil cannot be used (high temperature) or in pencil lead mixed with clay. Diamond is hard, used as abrasive. Fullerenes are nanomaterials, not lubricants. Coal is fuel.
Explanation:
Robert Millikan, along with Harvey Fletcher, performed the famous oil drop experiment in 1909. By observing the motion of tiny charged oil droplets in an electric field, Millikan accurately determined the elementary charge of a single electron to be approximately 1.592 × 10^-19 coulombs (later refined to 1.602 × 10^-19 C).
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