Answer: During the day, photosynthesis is dominant, so there is a net release of oxygen. At night, photosynthesis stops but respiration continues, so there is a net consumption of oxygen.
Explanation:
Answer:
Declining crude birth rates.
Explanation:
Birth rate may be defined as the number of births takes place per year per thousand of the population. The birth rate and death rate may change the population dynamics.
The developing countries shows the expanding population graph as they have more number of people of the reproductive age. The advancement in the medical field results in the decline birth rate that causes the decline of the nature resources.
Thus, the answer is declining crude birth rates.

velocity is a vector so it has a magnitude and direction so the answer would be B
Answer:
Mass
Explanation:
The larger a star's mass, the shorter it's lifespan.
I hope this helps! ☺
Answer:
Elements that are found in the same horizontal row (belong to the same period) in the periodic table, e.g. Fluorine and Neon both have the same energy level of 2.
<em>Note: The question does not specify any two elements.</em>
Explanation:
The modern periodic table is organized into eight vertical columns known as groups and seven horizontal rows known as periods. The atomic number ( number of protons in the nucleus) of elements increases when moving across the periodic table from left to right. The horizontal rows or periods represents an energy levels or the number of electron shells in an element. Energy levels (also called electron shells) are fixed distances from the nucleus of an atom where electrons may be found. Elements belonging to the same period have the same number of energy level or shells. For example, the elements belonging to Period 2 include lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine and neon. These all have the same number of energy level of 2.