Answer:
Scientists don't actually measure astronomical distances in light years. Rather, they measure them in a unit called the Parsec , and only convert to light years when they're talking to the general public . One light-year is the distance light travels through space in one year.
Explanation:
Answer:
= 28.745 g
Explanation:
Half life is the time taken by a radioactive element to decay by half the original amount.
Therefore;
New mass = Original mass × (1/2)^n
Where n is the number of half lives, in this case, n = 20/5.27 = 3.795
Therefore;
New mass = 399 g × (1/2)^3.795
<u> = 28.745 g</u>
I believe the major periodic trends include; electronegativity, ionization energy, electron affinity, atomic radius, melting point, and the metallic character. Periodic trends, arising from the arrangement of the periodic table, provide chemists with an invaluable tool to quickly predict an element's property.