Answer:
2.10 × 10⁹ yr
Step-by-step explanation:
The half-life of U-235 is the time it takes for half the U to decay.
After one half-life, half (50 %) of the original amount will remain.
After a second half-life, half of that amount (25 %) will remain, and so on.
We can construct a table as follows:
No. of Fraction Amount
<u>half-lives</u> <u>t/(yr × 10⁶)</u> <u>remaining</u> <u>remaining/g </u>
1 700 ½ 10.0
2 1400 ¼ 5.00
3 2100 ⅛ 2.50
4 2800 ¹/₁₆ 1.25
We see that 2100 × 10⁶ yr is three half-lives, and the amount of U-235 remaining is 2.50 g.
It takes 2.10× 10⁹ yr for the U-238 to decay to 2.50 g.
Answer:A
Explanation: because The nucleus directs all of the cell's activities, including reproduction.
Answer:
Explanation:
Law of conservation of mass:
According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.
This law was given by french chemist Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.
For example:
In given photosynthesis reaction:
6CO₂ + 6H₂O + energy → C₆H₁₂O₆ + 6O₂
there are six carbon atoms, eighteen oxygen atoms and twelve hydrogen atoms on the both side of equation so this reaction followed the law of conservation of mass.
Law of multiple proportion:
When two elements combine to form two or more compounds with different proportions, the weight of on element that combine with other elements in fixed proportion is in the ratio of small whole number.
For example:
Consider the example of carbon dioxide and carbon monoxide.
CO and CO₂
we are given with 1 g carbon on both case while 1.3 g oxygen for carbon monoxide and 2.6 for carbon dioxide. It means the ratio of oxygen is 1:2.
There is 1.3 g of oxygen in carbon monoxide for one g of carbon while in case of carbon dioxide there is 2.6 g of oxygen for one gram of carbon.
Answer:
A) solubility
B)luster
D)Density
F)magnetism
Explanation:
A physical property is one that tells us everything about what a substance is when no change is is occurring to its constituent.
Such properties can be observed with our senses or instruments or pieces of apparatus.
- Examples are luster, density, solubility, taste, odor, color, melting point, boiling point etc.
Answer:
C. A Spring Scale
Explanation:
Using process of elimination, we can quickly decide that a stopwatch and a ruler will not be useful in measuring the force. This leaves us with either the spring scale or a balance scale. A balance scale is used to compare two weights, so this is eliminated. That leaves us with a spring scale. This is because we can attached the spring scale to the car and when we let it go, we can record the force. I hope this helps!