The property of all ionic compounds that makes chalk particularly useful for writing on a chalkboard is : Hardness and Brittleness
Those properties make chalk leaves residues on the board every time friction happen between the chalk and the board
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Half life formula
The number of unstable nuclei remaining after time t can be determined according to this equation:
N(t) = N(0) * 0.5^(t/T)
where:
N(t) is the remaining quantity of a substance after time t has elapsed.
N(0) is the initial quantity of this substance.
T is the half-life.
It is also possible to determine the remaining quantity of a substance using a few other parameters:
N(t) = N(0) * e^(-t/τ)
N(t) = N(0) * e^(-λt)
τ is the mean lifetime - the average amount of time a nucleus remains intact.
λ is the decay constant (rate of decay).
All three of the parameters characterizing a substance's radioactivity are related in the following way:
T = ln(2)/λ = ln(2)*τ
How to calculate the half life
Determine the initial amount of a substance. For example, N(0) = 2.5 kg.
Determine the final amount of a substance - for instance, N(t) = 2.1 kg.
Measure how long it took for that amount of material to decay. In our experiment, we observed that it took 5 minutes.
Input these values into our half life calculator. It will compute a result for you instantaneously - in this case, the half life is equal to 19.88 minutes.
If you are not certain that our calculator returned the correct result, you can always check it using the half life formula.
Answer:
the fourth one. biomagnofication is when an organism ingests other plants or animals that have toxins in them. the toxins are widely distributed
Answer:
please give me brain list and follow
Explanation:
The main function of the cell nucleus is to control gene expression and mediate the replication of DNA during the cell cycle. The nucleus is an organelle found in eukaryotic cells. Inside its fully enclosed nuclear membrane, it contains the majority of the cell's genetic material.
Because water can absorb and transfer heat well, the human body uses it to stabilize temperature. Water has a relatively high heat capacity, meaning it can absorb a lot of heat before its temperature rises. ... Water also helps expel excess heat from the body as water vapor from the lungs and sweat on the skin.
The first sentence is the answer and the other ore explanation
