The correct answer is internal.
A solid substance whose components like molecules, atoms, or ions are aligned in a highly ordered microscopic composition producing a crystal lattice, which extends in all the directions is known as a crystalline solid or a crystal.
On the other hand, the noncrystalline solid substance in which the atoms and molecules are not aligned in a definite lattice pattern is known as an amorphous solid. Such solids comprise plastic, glass, and gel.
The given chemical reaction is between calcium carbonate and hydrochloric acid to produce calcium chloride, carbon dioxide and water. This reaction can be represented as,
When the concentration of the reactants is increased, the number of collisions that take place between the reactant molecules increases. This speeds up the reaction. Therefore, when the concentration of HCl is doubled as long as there is enough calcium carbonate to react with HCl, the number of effective collisions giving products increases, this causes the rate of forward reaction to increase.
Answer : 
is the molecule that exhibit dipole-dipole forces as its strongest intermolecular force.
Explanation : The shape or geometry of given molecules of 
, 
, 
, 
and are linear, linear, tetrahedral, trigonal planar and angular respectively.
The given molecules , , , are symmetrical molecules. These symmetric molecules cannot exists as dipole even they contain polar bonds. Thus, these molecules will not exhibit dipole-dipole forces.
molecule has polar bonds and unsymmetrical bonds as shown in attached image. This molecule cannot exhibit H-bonding. It exhibit only dipole-dipole forces.
Therefore, molecule exhibit dipole-dipole forces as strongest intermolecular force.
Answer and explanation:
Initially, the pH of the solution will be determined by the dissociation of the weak acid.
Usually, this kind of solution consists of a mixture of weak acid that has not yet reacted and the salt that will be formed by the reaction of the weak acid with a strong base that has been added.
After the dissociation process, the pH will be more affected due to the excess of base in the solution.
