Answer:A): four electron shells
Explanation:
In the period table, atoms are arranged in rows called periods and columns called groups. The arrangement of atoms in groups is based on the number of their valence electrons while the arrangement of atoms across the periods is based on their number of electrons shells. Atoms are arranged across the periods in increasing order of their atomic number i.e., according to their number of electrons. Potassium has 19 electrons while copper has 29 electrons. Both has four electrons shells according to their electronic configuration.
Many ecological phenomena are difficult to study because they can take long periods of time or have large spatial scales.
1) A 2) B
Explanation:
Enzymes are catalyst, meaning that they could be use in several reaction and they speed up any chemical reaction rate. So knowing this, when the animal have more enzymes it will react more quickly with the food, making it digest the food more quickly.
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Cold dry air sinks below the warm wet air and it pushed upwards
Letter (A.)
Diffusion<span> in </span>cells<span>. Materials like oxygen, carbon dioxide and glucose enter and </span>leave cells by diffusion<span>. When a </span>cell<span> is respiring the concentration of oxygen and glucose inside the </span>cell<span> is lower than the surrounding blood so these </span>substances<span> move into the </span>cell<span>.
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