Explanation:
OK, first of all, let me explain to you, what is a scientific theory...
A scientific theory is an explanation and demonstration of an aspect that exists in the natural world or universe that has been verified by the scientific way through repeated testing of the experiment with accepted protocols of observation, measurements and evaluation of results.
A scientific law is generated in the same procedure as above, but it can predict a wide range of natural phenomena.
Ex-: you are throwing a basketball from the top of a dam to the river. according to physics on earth, it should fall down. it's a law. no matter where you are, that basketball touches down the ground if there's any gravitational force.
But cell theory cannot be assumed to be common throughout the entire universe. Because we may find some other form of life that has some other plans. viruses are not obeying this theory.
*In a nutshell, a law is stable from its' origin. most of the time, it won't change. but theories will change with updating facts of science.
Answer:
Yes, the model of the helium atom is showing an ion.
Explanation:
Helium, with an atomic number of 2, should have 2 protons and 2 electrons; however, the model only depicts 1 electron. That means the helium must have lost an electron, making it a +1 charge and an ion.
Have a developmentally more mature understanding of death
The four important characteristics of respiratory surface are:
1. Thin walls
2. Moisture
3. Large surface area
4. Blood supply
Respiratory system or respiratory tract is divided into upper and lower tract. Upper respiratory tract includes nose and its cavities, sinuses, pharynx and the part of the larynx. Lower respiratory tract consists of the trachea, bronchi, bronchioles and the alveoli.
Alveoli are the ends of the respiratory tract the smallest units in it. Alveoli are small folded air sacs that are branching off from alveolar ducts and providing an extremely large surface area for the gas exchange. Gas exchange occurs thanks to small blood vessels – capillaries that surround alveoli and it occurs via the process of diffusion.
So, respiratory surface is thin membrane also known as the blood–air barrier that consists of the alveolar epithelial cells, their basement membranes and the endothelial cells of the alveolar capillaries.
