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.
Complete question is;
Chemical reactivity of alkali metals increases down the group while reactivity of halogens decreases down the group. Give reasons
Answer:
Explained below
Explanation:
Alkali metals exhibit reactivity due to their electropositivity. Now, for alkalis, their electro-positivity increases down their group. Since their reactivity increases with increase in electropositivity, it means their reactivity also increases down the group.
Whereas, the reactivity of halogens occurs as a result of their electronegativity. Now, electronegativity for halogens decreases down the group. Since their reactivity decreases with decrease in electronegativity, it means that their reactivity will also decrease down the group.
Answer:
c when electrons drop down from a high energy level they emit a photon.
Explanation:
The answer is B!! hope this helps(: an example is a zebra or a lion
Answer:
When the volume of product increases.
When the weight of the product decreases.
Option (a) and (d) are correct.
Explanation:
The overall density of the product can be decreased:
a. Increase the volume of the product (and keep the material same)
d. Decrease the weight of the product ( and keep the same material ).
Density is calculated as the ratio of mass to the volume.
Density is inversely related to volume and directly related to mass.
So, when the mass of the product is increased then the density will increase keeping the material same. Density will also increase when the volume of the product decreased.
