Answer:
Choice number two: this element is malleable and ductile.
Explanation:
A modern periodic table can be split into three sections:
(from left to right)
- Metals,
- Metalloids, and
- Nonmetals.
Based on the descriptions, section A likely refers to the metals. Section B likely refers to metalloids. Section C likely refers to nonmetals.
Metals are malleable and ductile. They are good conductors of electricity.
The reason is that in a metal, the valence electrons do not belong to some specific atom. Rather, the metal cations share these electrons. The electrons are free to move around the metal and conduct electricity.
Ionic compounds like table salt are brittle. The reason is that when an ionic compound is deshaped, ions of the same charge come directly into contact with each other. That creates repulsion and cracks the crystal. In contrast, the metal cations in a metal won't come into contact with each other. Electrons would rapidly fill the gap between these cations, so the metal won't crack. That's why unlike ionic compounds, metals are malleable and ductile.
The melting points of metals can vary significantly. Indeed, the mercury (
, a metal) is a liquid at room temperature. In contrast, tungsten (
, also a metal) won't melt until it is heated to over
.
Answer:
A
Explanation:
A common example of heterogeneous catalysis is the hydrogenation reaction of simple alkenes. The conversion of ethene (C2H4) to ethane (C2H6) can be performed with hydrogen gas in the presence of a metal catalyst such as palladium (“Conversion of Ethene to Ethane with Hydrogen and a Metal Catalyst”).
44÷22=2 g/cm3 so A is correct answer
Answer:
The letter or letters that represent an element are called its atomic symbol. The numbers appearing as subscripts in the chemical formula indicate the number of atoms of the element immediately before the subscript. If no subscript appears, one atom of that element is present
Explanation:
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When using the formula: <span>n = m / M
n = moles
m = mass (g)
M = molar mass (g mol^-1)
</span>
The answer is C) 638