Answer:
It demonstrates that it a physical change because you can't see nothing happening but something happening
Sry if it doesn't make sense
Answer: a rection will most likely occur if the colliding partilces have the proper orientation and energy.
The reactions occur becasue the molecules collide.
But not all the collisions result in a reaction.
The collisions have to meet some requirements.
Two of the basic requirements is that the collision has enough energy to overcome the activation energy and that the molecules collide in the riight way.
When two molecules react it is necessary that one element of one of the molecules interact when a specific element or group in the other molecule. That is the orientation must be the right one.
Collisions that to not have the proper orientation or enough energy will not cause reaction (changes in the bonds of the molecules).
This problem is honestly, very easy. Just grab a periodic table and find the element in Group 1 and Period 7. But first, let's discuss how the elements are arranged systematically in a periodic table. There are a lot of scientists who contributed to it, but the most famous one is Dimitri Mendeleev. He arranged the elements according to their atomic number. The elements starts from 1 which is Hydrogen up to the heaviest known elements which is Oganesson with an atomic number of 118. As you can observe, there is a gap between groups 3 and 4. This is done so that the periodic table does not take too much space horizontally. Thus, they are just placed at the bottom. These elements are called lanthanides (upper row) and actinides (lower row). The rows in the periodic table are called groups, and the columns are called periods.
Now, the element at the lower left corner (Group 1, Period 7) is Francium, abbreviated as Fr. It has an atomic number of 87. Some elements are actually synthesized, but Francium is a naturally occurring radioactive element. It was discovered by Marguerite Perey in France.
This is a really hard question. Because if you change it to 1,000 then that's only one. If you add the decimal so it's 1,000. , then that's 4 if you change it to 1,040, that's 3. So you can not change that to 2 significant digits.
A substance that stabilizes an emulsion, in particular a food additive used to stabilize processed foods.