C. The number of Valence electrons,
Every atom tries to follow the Octet rule i.e To have 8 electrons in its Valence shell.
Every atom tries to accomodate 8 electrons in its Valence shell to stabilize themselves, Metals usually have 1-3 eletrons in their Valence shell which they donate to non metals so their Valnce shell has 8 electroons, (The previous will now be the Valence shell and it will be full)
Similarly Non metals have 4-7 electrons, they accept electrons from metals so they can have 8 electrons in their Valence shell.
Noble gases already have 8 electrons in their Valance shell, so they do not react and stable.
Hope it helps :)
It’s Thai right? I want to help but don’t know how to answer this question.
The correct option is D.
During peptide formation, when two amino acids come together, a hydrogen atom and two molecules of oxygen are released in form of water molecules. The amino acid that present the carboxyl group to the reaction loses an hydroxyl group while the amino acid that present the amino group to the reaction loses a hydrogen.
Most solids a) are dense and difficult to compress.
Most solids are closely compacted, their molecules are close together and vibrate. They don't move freely like gas or water molecules do.
They are difficult to be squeezed or flattened.
Answer:
Density, D = 2g/cm^3
Explanation:
Given the following data;
Length = 2cm
Width = 3cm
Height = 2cm
Mass = 24g
Density = ?
Volume of a rectangular solid (V) = Length × Weight × Height
Therefore, V = L× W × H
Substituting the values, we have;
V = 12cm
Density can be defined as the ratio of mass to volume i.e mass all over volume.
Mathematically, 
Substituting the values, we have;
<em>Density, D = 2g/cm^3</em>
Hence, the density of the rectangular solid is 2g/cm^3.
