Answer:
64.52 mg.
Explanation:
The following data were obtained from the question:
Half life (t½) = 1590 years
Initial amount (N₀) = 100 mg
Time (t) = 1000 years.
Final amount (N) =.?
Next, we shall determine the rate constant (K).
This is illustrated below:
Half life (t½) = 1590 years
Rate/decay constant (K) =?
K = 0.693 / t½
K = 0.693/1590
K = 4.36×10¯⁴ / year.
Finally, we shall determine the amount that will remain after 1000 years as follow:
Half life (t½) = 1590 years
Initial amount (N₀) = 100 mg
Time (t) = 1000 years.
Rate constant = 4.36×10¯⁴ / year.
Final amount (N) =.?
Log (N₀/N) = kt/2.3
Log (100/N) = 4.36×10¯⁴ × 1000/2.3
Log (100/N) = 0.436/2.3
Log (100/N) = 0.1896
Take the antilog
100/N = antilog (0.1896)
100/N = 1.55
Cross multiply
N x 1.55 = 100
Divide both side by 1.55
N = 100/1.55
N = 64.52 mg
Therefore, the amount that remained after 1000 years is 64.52 mg
Given:
<span>M1 = 6.5 kg of books
</span><span>M2 = 1.5 kg of CDs
</span><span>M3 = 2.0 kg of DVDs
Required: percent by mass of each object
Solution:
First, we calculate the total mass.
M = 6.5 kg + 1.5 kg + 2.0 kg = 10 kg
Percent by mass is calculated by getting the ration of the mass of an object and the total mass multiplied by 100 to get the percent.
%M1 = 6.5 / 10 x 100 = 65%
%M2 = 1.5/10 x 100 = 15%
%M3 = 2.0/10 x 100 = 20%</span>
Try adding spaces next time! That's iodine. Check all of the numbers to make sure all of the orbitals are filled, then find the ones which aren't. In this one, only the 5p5 subshell isn't full. 5p5 is the fifth row on the right side, count across the nonmetals and metalloids until the fifth one (a halogen). That's iodine, and that's your answer!
Answer:
Ca²⁺ + 2 OH⁻ → Ca(OH)₂(s)
Explanation:
In chemistry, the net ionic equation is a way to write a chemical reaction whereas you write only the ions that are involved in the reaction.
When calcium chloride, CaCl₂ reacts with sodium hydroxide, NaOH to produce Ca(OH)₂ the only ions involved in the reaction are Ca²⁺ and OH⁻, thus, the balanced net ionic equation is:
<em>Ca²⁺ + 2 OH⁻ → Ca(OH)₂(s)</em>
<em>Cl⁻ and Na⁺ are not involved in the reaction and you don't have to write them.</em>
<u>Out of all given option, the following statements are true about a system:</u>
- A system is a group of objects analyzed as one unit.
- Energy that moves across system boundaries is conserved
Answer: Option A and B
<u>Explanation:</u>
A system is "a complicated item whose parts or segments are identified with probably a portion of different segments", it very well may be material or calculated. All systems have piece, structure, and condition, yet just material systems have instruments (or forms), and just some material systems have shape.
As per systems, all articles are systems or segments of another system. For instance, a nuclear core is a physical material system made out of protons and neutrons related by solid atomic association; a cell is a natural material system made out of related organelles by non-covalent synthetic securities and metabolic pathways; and a logical hypothesis is a consistent reasonable system made out of theories, definitions, and hypotheses related by relationship and conclusion.
