Answer:
D. Black Holes
Explanation:
Black holes are large objects that form dense gravity wells in space. Their gravitational pull is so strong that even light cannot escape it.
The general equation for radioactive decay is;
N = N₀e^(-λt)
x - decay constant (λ) - rate of decay
t- time
N - amount remaining after t days , since we are calculating the half life, amount of time it takes for the substance to to be half its original value, its N₀/2
N₀ - amount initially present
substituting the values
N₀/2 = N₀e^(-0.081t)
0.5 = e^(-0.081t)
ln (0.5) = -0.081t
-0.693 = -0.081t
t = 0.693 / 0.081
= 8.55
half life of substance is 8.55 days
The compound solubility which will not be affected by a low pH in solution is AgBr.
<h3>What is pH?</h3>
pH is a measure of the acidity or basicity of any solution and according to the pH scale 0 to 6.9 shows the acidity, 7 is neutral and 7.1 to 14 shows the basicity of any solution.
- AgBr is sparingly soluble in water and not soluble in acids, so if we low the pH of the solution towards the acidity its solubility not affected.
- NiCO₃ is a basic salt and and shows solubility in the acidic medium so change in pH will affect its solubility.
- Co(OH)₂ it is also a basic compound and shows its solubility in the acidic medium and get affected when change in pH takes place.
- PbF₂ is a strong base and also shows solubility in the acidic medium easily, so get affected when change in pH takes place.
- In CuS, sulphide is basic ion and whole compound shows solubility in the acidic medium and get affected when low pH of solution takes place.
AgBr is not affected by a low pH in solution.
To know more about solubility, visit the below link:
brainly.com/question/23946616
Answer:-
As we can see from the graphical data,
The distance covered by all the four runners is the same 5 km.
Among the four athletes, Athlete P covers the distance in under three hours.
It is the minimum time taken among the four athletes.
Thus Athlete P covers the 5 km distance in the minimum amount of time.
We know that speed = 
Since time taken for P is minimum, his speed is the maximum. P ran the fastest.
Time taken by Q = 4.5 hours.
Speed of Q = 
= 
= 1.1 km/ hr
Time taken by R = 6 hours.
Speed of R = 
= 
= 0.8 km/ hr
