Answer :
During diffusion, when the concentration of the molecules on both sides of the membrane is the same, the molecules will continue to move across the membrane in both the direction.
Answer 3 : It allows single-celled organism to reproduce, and other organism to repair damage tissues and grow.
Answer 4: The nucleus is an organelle that is surrounded by the cytoplasm, a jelly-like fluid.
Explanation :
Diffusion : It is a process where liquid moves from higher concentration to the lower concentration through permeable membrane.
When the concentration of the molecules on both sides of the membrane is same and the membrane is permeable membrane then diffusion will occur and the molecules will moves continuously across the membrane in both the direction.
Answer 3 :
Mitosis : It is a process of cell division. In this process, nucleus divides into two daughter cell and each daughter cell contains same number of chromosomes as present in parent nucleus.
The main purpose of the mitosis is to repair damaged tissues and growth.
Answer 4 :
Nucleus is a type of cell organelle. It is present in both animal and plant cells and it is the brain of the cell. It is present only in eukaryotic cell.
Nucleus is an organelle which is surrounded by the cell membrane which protects its from the other cells.
Cytoplasm is a jelly-like fluid which is present in the cell membrane which is made up of salt and water.
My guess on that molecule is nucleus , sorry if it’s not correct
Density is the mass of compound divided by its volume can be shown as follows:


40 mL of snow having 20 g of mass calculated from density.
Now, 10 cm of snow = 3.93 inches = 20 g
As, 10 inches of rain will produce 11 inches of ice as the volume of ice is bigger than rain water.
10 inches rain = 11 inches snow
3.93 inches of snow produced by

Thus, 3.57 incehs of rain produces by 10 cm snow.
<h2>
Hello!</h2>
The answer is:
The empirical formula is the option B. 
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Why?</h2>
The empirical formula of a compound is the simplest formula that can be written. On the opposite, the molecular formula involves a variant of the same compound, but it can be also simplified to an empirical formula.

We are looking for a formula that cannot be simplified by dividing the number of molecules/atoms that conforms the compound.
Let's discard option by option in order to find which formula is an empirical formula (cannot be simplified)
A. 
It's not an empirical formula, it's a molecular formula since it can be obtained by multiplying the empirical formula of the same compound.

B. 
It's an empirical formula since it cannot be obtained by the multiplication of a whole number and the simplest formula. It's the simplest formula that we can find of the compound.
C. 
It's not an empirical formula, it's a molecular formula since it can be obtained by multiplying the empirical formula of the same compound.

D. 
It's not an empirical formula, it's a molecular formula since it can be obtained by multiplying the empirical formula of the same compound.

Hence, the empirical formula is the option B. 
Have a nice day!
The mass number is the number of protons plus the number of neutrons. Since there are 16 neutrons, there are 14 protons. This also corresponds to the atomic number, so this atom's atomic number is 14 which is also Silicon