a usually irreversible chemical reaction involving the rearrangement of the atoms of one or more substances and a change in their chemical properties or composition, resulting in the formation of at least one new substance: The formation of rust on iron is a chemical change. Chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. These processes are called chemical reactions and, in general, are not reversible except by further chemical reactions.
Answer:
3.125% will remain after 125 days
Explanation:
Given data:
Half life of Th-234 = 25 days
Percent of thorium remain after 125 days = ?
Solution:
Number of half lives = T elapsed / half life
Number of half lives = 125 days / 25 days
Number of half lives = 5
At time zero =100%
At 1st half life = 100%/2 = 50%
At second half life = 50%/2 = 25%
At third half life = 25%/ 2 = 12.5%
At 4th half life = 12.5% /2 = 6.25%
At 5th half life = 6.25% /2 = 3.125%
Answer & Explanation:
The law of multiple proportion states that two elements A and B can react with each other to form multiple compounds while one of the two elements remain fixed.
For Example
Hydrogen reacts with oxygen to form:
Water (H2O)
Hydrogen peroxide (H2O2)
The cork is less dense than the water
