Answer:
6 days 
Explanation:
The following data were obtained from the question:
Original amount (N₀) = 100 mg
Amount remaining (N) = 6. 25 mg
Time (t) = 24 days 
Half life (t½) =?
Next, we shall determine the decay constant. This can be obtained as follow:
Original amount (N₀) = 100 mg
Amount remaining (N) = 6. 25 mg
Time (t) = 24 days 
Decay constant (K) =? 
Log (N₀/N) = kt / 2.303
Log (100/6.25) = k × 24 / 2.303
Log 16 = k × 24 / 2.303
1.2041 = k × 24 / 2.303
Cross multiply 
k × 24 = 1.2041 × 2.303 
Divide both side by 24
K = (1.2041 × 2.303) / 24
K = 0.1155 /day
Finally, we shall determine the half-life of the isotope as follow:
Decay constant (K) = 0.1155 /day
Half life (t½) =? 
t½ = 0.693 / K
t½ = 0.693 / 0.1155
t½ = 6 days 
Therefore, the half-life of the isotope is 6 days 
 
        
             
        
        
        
Prominent copper sulfide minerals include Cu2S (chalcocite) and CuS (covellite).
        
             
        
        
        
Remember that any intersection of lines is a C, and that the number of hydrogens attached are the necessary to complet the 4 bonds.
1) CH3 - CH (OH) - CH (CH3) -CH3
2) CH3 - O - CH(CH3)-CH2 - CH3
I have used the parenthesis to indicate that the radical inside is in other branch, bonded by a single line - 
        
             
        
        
        
 Answer:
1. Reflex Conditioning
Explanation:
Conditioning is an aspect of learning where a stimulus works effectively in producing a response from an organism. This response becomes regular given the type of reinforcement that is administered to the organism. The reinforcement is usually a reward that is given to the organism. 
This is what is observed in the woodpecker.  The stimulus or reinforcement which proves effective in producing a continuous response  from the woodpecker is the abundant supply of the birds favorite bugs. This reinforcement makes it possible for the woodpecker to become conditioned towards returning to the tree.