Rare earth elements are a series of chemical elements found in the earth's crust and are vital to many of the modern technologies in the world such as computers and networks, advanced transportation and consumer electronics. They help fuel economic growth, maintain high living standards and even save lives. Examples include:
Scandium. Used in television and fluorescent lamps.
Yttrium. Used in cancer treatment drugs, superconductors and camera lenses
Lanthanum. Used to make special optical glasses, telescope lenses and also in petroleum refining.
Neodymium. Used in making some of the strongest permanent magnets, found in most modern vehicles and aircraft.
<u>Answer:</u> The correct answer is 1.18 g.
<u>Explanation:</u>
We are given a chemical equation:
We know that at STP conditions:
22.4L of volume is occupied by 1 mole of a gas.
So, 2.21L of carbon dioxide is occupied by = 
of carbon dioxide gas.
By Stoichiometry of the above reaction:
1 mole of carbon dioxide gas is produced by 1 mole of carbon
So, 0.0986 moles of carbon dioxide is produced by = 
of carbon.
Now, to calculate the mass of carbon, we use the equation:
Moles of carbon = 0.0986 mol
Molar mass of carbon = 12 g/mol
Putting values in above equation, we get:
Hence, the correct answer is 1.18 g.
Answer:
To have a high electrical conductivity, a normal metal should have mobile valence electrons and a long electron mean free path.
Explanation:
A long mean free path means that the electron goes a long distance between scattering events.
The answer is NH3 an NH4+.
Buffer solutions contain a weak base and its conjugate acid or a weak acid and its conjugate base. NH3 is a weak base and NH4+ is its conjugate acid.
