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 : Option 4) 
Explanation : is the only sample of matter which can be classified as a solution. As the solution can be defined as a liquid mixture which contains a minor component (the solute) that is uniformly distributed within the major component (the solvent).
In this case, the solute is 
which is dissolved in water which acts as an solvent. Also, it has a subscript which is aq. which means aqueous, is often given to the solution in which the solvent is water.
Therefore, is the correct answer.
The correct name for the N3- ion is a nitride ion.
Answer:
Volume = 30cm³
Explanation:
A block is a geometrical figure and its volume, -look at the figure-, follows the equation:
Volume = Width*Length*Height
As the measurements of the block are 5.00cm, 3.00cm and 2.00cm, the volume is:
Volume = 5.00cm*2.00cm*3.00cm
<h3>Volume = 30cm³</h3>
