Explanation:
1) Thermal and Electric conductivity
2) Metallic strength
Answer:
A. Compounds
Explanation:
Firstly, don't let the word "pure" confuse you; this is pretty much irrelevant to the question.
The key to answering this question lies in "substance" and "more than one type of element chemically bonded."
Something you ought to memorize is that a substance is either an element or compound. Therefore, you can eliminate choices B./C.
Next, use the part of the definition that says "more than one type of element chemically bonded" to conclude that it's a compound. Not only is this the definition of a compound, but the fact that is says <em>more than one type of element</em> should automatically tell you that it is different from just a regular element (Choice D.).
Answer:
Wavelength, 
Explanation:
Given that,
Frequency, 
We need to find the wavelength of a photon of light. The relation between frequency and wavelength is as follows :

So, the wavelength of the light is
.
Melting is equivalent to freezing: a temperature when a solid become a liquid.
Answer: I think the right answer is c