Answer:
Foam fight is a chemical change.
Explanation:
Please give me brainliest :)
The definition of a gem is "a precious stone, cut and polished for jewelry. They are all minerals. Some highly desirable gemstones may not be suitable for jewelry, yet be very collectible, like sphene. Others, like those in the corundum family, are prized for color and hardness, like emeralds and diamonds. Further, some common minerals, when polished, make beautiful pieces. With all that said, i woukd go with rarer.
Answer:
Explanation:
a )
m = m₀ 
m is mass after time t . original mass is m₀ , λ is disintegration constant
λ = .693 / half life
= .693 / 1590
= .0004358
m = m₀ 
b )
m = 50 x 
= 40.21 mg .
c )
40 = 50 
.8 =
= 1.25
.0004358 t = .22314
t = 512 years .
11. ionic charge +1, helium.
12. ionic charge 2-, neon.
13. ionic charge 3+, neon.
