Question

An unknown substance has a melting point of 1064 ∘C, is insoluble in water, conducts electricity as a solid, and is hard. Given these properties, which of the following are possible identities for the unknown substance? Check all that apply.
Check all that apply.
A. SiO2
B. F2
C. Au
D. KBr

Answer 1

Answer:

The unknown substance is Au ( gold)

Explanation:

SiO2 has a high melting point, is insoluble in water but is a very poor conductor. So the statements do not apply here.

F2 is soluble in water, has a melting point way lower than 1064 °C, and isa gas. F2 doesn't apply here.

Au is insoluble in water, has a high melting point, is a good conductor and is hard. Gold applies are all those statements.

Kbr is good soluble in water, and is a bad conductorbecause  it is just a powder, and the molecules have no mobility, and therefore it cannot conduct electricity. The unknown substance is not Kbr.

The unknown substance is Au ( gold)