The correct statement is that Example A describes a chemical change and Example B describes a physical change.
Explanation:
In example A we have a chemical change because the use of soaps and detergents implies a chemical reaction called saponification due to the soap molecules has a double component the first part of a soap is called hydrophilic and the second part is called hydrophobic. so, when the soap molecules interact with the oil molecules in water the hydrophilic part will be bonded with water and the hydrophobic part will be bonded with the oil. This new bondings are called micelles and the formations of micelles by new bonds it is a chemical change.
In example B there is a physical change because the water in a Bowl is evaporated. it means that at higher temperatures the molecules of water pass from the liquid state of the matter to the gas state. This physical change happens after the water molecules reach enough energy able to broke surface tension in liquid water. This energy is obtained thanks to the increasing of temperature, and the temperature needed to achieve this change from liquid to gas is called boiling point.
Add copper (II) oxide (insoluble base), a little at a time to the warm dilute sulfuric acid and stir until the copper (II) oxide is in excess (stops disappearing) Filter the mixture into an evaporating basin to remove the excess copper (II) oxide. Leave the filtrate in a warm place to dry and crystallize.
Usually the presence of a dominant version of allele masks the expression of a recessive allele. A recessive allele is only phenotype is only expressed when 2 recessive alleles combine.
