Answer:
Explanation:
count given by old sample = .97 disintegrations per minute per gram
count given by fresh sample = 6.68 disintegrations per minute per gram
Half life of radioactive carbon = 5568 years
rate of disintegration
dN / dt = λ N
In other words rate of disintegration is proportional to no of radioactive atoms present . As number reduces rate also reduces .
Let initial no of radioactive be N₀ and after time t , number reduces to N
N₀ / N = 6.68 / .97
Now
λ is disintegration constant
λ = .693 / half life
= .693 / 5568
= .00012446 year⁻¹
Putting the values in the equation above
1.929577 = .00012446 t
t = 15503.6 years .
Answer:the answer is A I think, tell me if I’m wrong
Explanation:
Answer:
Water - H2O
Ammonia - NH3
Sulfur dioxide - SO2
Hydrogen sulfide - H2S
Ethanol - C2H6O
Explanation:
Those are some atoms with polar covalent bonds. Hope this helps!!
Answer:
Two different changes have occurred in the beaker. The description of the step 1 suggests that most likely a <u>chemical change</u> has occured while the description of the step 2 correspond to a<u> physical change</u>.
Explanation:
When the mixture of two liquid colorless substances results in the appearance of solid particles you first thing in the appareance of a new substance. If this is the case, it means that the original substances reacted chemically to form a new product, so this is a chemical change.
On the other hand, the second step describes just a physical change as it has been just that the yellow particles settled and then a physical separation by <em>decantation</em>. Decantation does not change the chemical properties of the particles settled, they are jsut separeated from the liquid. During this step both the yellow particles and the liquid in the beaker keep their chemical properties, so this is just a physical change.
