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.
Lead is said to have a face centered cubic crystal structure. So, it would have four atoms per cell where 3 of the atoms are at the faces and 1 atom constitutes the corner of the unit cell. So, that the diagonal of one face of the cell is equal to 4 times the radius. To determine the measurement of the radius, we calculate the volume from the density given.
Density = 11.3 g / cm^3 = 207.2 g / mol ( 4 atoms / cell ) / 6.022x10^23 atoms / mol (V cm^3/ cell)
Calculating for V,
V = 1.21795 x 10^-22 cm^3
V = a^3 where a is the edge length
a = ∛1.21795 x 10^-22 cm^3
a = 4.9569x10^-8 cm
diagonal = 4r
r = diagonal / 4
where diagonal = √2a^2 = a√2
r = a√2 / 4 = 1.7525x10^-8 cm
B. Earth’s tilt
Earth’s tilt exposes different parts of the earth to varying degrees of sunlight throughout the year, causing seasons.
Sorry this is late but I will cause energy transformation
hope this helps :))
Answer: b
Explanation: because b is the right one i just did it.
