Answer:
It will take 28.5 minutes
Explanation:
<u>Step 1: </u>Data given
Mass of Cu = 4.50 grams
8.00 A of current are used
Molar mass of Cu = 63.5 g/mol
Step 2: Calculate time needed
Cu2+ →Electricity → Cu
we notice a flow of 2 electrons ⇒ This means the Faraday constant = 2F
Since Molar mass of Cu is 63.5 g/mol
63.5 grams of Cu is deposited by 2*96500 C
4.50 grams of Cu ((2*96500)/63.5) * 4.50 = 13677.17 C
Q = It
13677.17 = 8t*60 seconds
t = 28.5 minutes
Hence, it is less preferrable to choose an isotope to enter your body, which will emit radioactivity for a long time, so we tend to choose isotopes, the radioactivity of which ceases quickly, so that the least possible amount of damage is caused to the cells
Answer:
This phenomenon occurs because the door, being metal and leading to changes in temperature, undergoes proportional and morphological changes, metals face expansion and expansion in the presence of heat, called thermal expansion.
On the other hand, against the cold, thermal contraction is suffered, that is why its volume decreases, and it contracts.
Explanation:
The expansion phenomenon of the door is not linear, since it increases its volume in width and height, therefore simultaneously on the entire surface.
When an area or surface expands, it does so by increasing its dimensions in the same proportion. For example, a metal sheet increases its length and width, which means an increase in area. Area dilation differs from linear dilation in that it involves an increase in area.
The area expansion coefficient is the increase in area that a body of a certain substance experiences, with an area equal to unity, as its temperature rises one degree centigrade. This coefficient is represented by the Greek letter gamma.
Regarding shrinkage, a clear example of this is when a metal foundry or a weld shrinks, sometimes it is difficult to understand with examples like these (doors) because it is little noticeable by our eyes and the dimensional changes for our perspective. it is infima.
Answer:
The correct answer is B.
Explanation:
The molecule of water has 2 atoms of hydrogen and 1 atom of oxygen.
The ratio of masses are given as:
This illustrates the law of definite proportions which is also known as law of constant compositions .
The law states that 'the elements combining to form compound always combine in a fixed ratio by their mass.'
Whereas :
Law of multiple proportion states that when two elements combine with each other to form more than one compounds , the mass of one element with respect to the fixed mass of another element are in ratio of small whole numbers.
Law of conservation of mass states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form.
In a balanced chemical reaction ,total mass on the reactant side must be equal to the total mass on the product side.
Law of conservation of energy states that energy can neither be created nor be destroyed but it can only be transformed from one form to another form.
