Molecules with identical molecular formulae but with different structural formulae are called_____.
A. Isotopes
B. Isomers
C. Electrode
D. Compound
Bronze is an alloy of_____.
A. Iron, Carbon
B. Copper, Tin
C. Nickel, Zinc
D. Mercury, Lead
The most abundant element in the earth’s crust is oxygen. The second most abundant element in the earth’s crust is_____.
A. Hydrogen
B. Nitrogen
C. Brass
D. Silicon
A person seated in front of a fire receives heat by_____.
A. Conduction
B. Convection
C. Radiation
D. None of these
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