Answer:
I think it's fungus or plant cell
Hydrogen because it only has one electron
Answer:

Explanation:
Given that,
The mass of the rock, m = 15 g
The volume of the rock, V = 10 cm³
We need to find the density of the rock. The density of an object is equal to the mass per unit volume such that,

So, the density of the rock is equal to
.
The postulate of Dalton's atomic theory that atom is indivisible particle and can be subdivided into smaller particles was later changed because atom can be divided into neutrons, protons and electrons. It was changed because after later finding out that the atom can be divided, the theory was changed to the correct finalized theory.
Hope this helps!!!
Answer:
Helium nuclei is emitted during alpha decay.
Explanation:
Alpha radiations are emitted as a result of radioactive decay. The atom emit the alpha particles consist of two proton and two neutrons. Which is also called helium nuclei. When atom undergoes the alpha emission the original atom convert into the atom having mass number 4 less than and atomic number 2 less than the starting atom.
Properties of alpha radiation:
Alpha radiations can travel in a short distance.
These radiations can not penetrate into the skin or clothes.
These radiations can be harmful for the human if these are inhaled.
These radiations can be stopped by a piece of paper.
Example:
₉₂U²³⁸ → ₉₀Th²³⁴ + ₂He⁴ + energy