About 12 hours is the time between a morning high tide and the next high tide
Explanation:
The Earth’s rotation happens between two tidal bulges
The “periodic rise and fall” of the surface water levels of the ocean is called tides. The gravitational action and interaction on the earth by the sun and the moon causes these tides. Different regions of the World experiences different patterns of tides like the diurnal, semi-diurnal etc.
When there is one high and one low tide occurring on a lunar day, then it is diurnal pattern. Semi-diurnal pattern occurs when there are two equal high and low tides on a single lunar day.
Since the Earth’s rotation happens between two tidal “bulges” on each lunar day, the coastal areas can experience two high and two low tides in every 24 hours plus 50 minutes.
Accordingly the time between two high tides would be 12 hours plus 25 minutes. Similarly, the time gap between a high to low tide would be 6 hours plus 12.5 minutes.
Number three
They contain protons (positive), neutrons (negative), electrons (neutral) and all are in a nucleus which is part of an atom
<u>Answer:</u>
For a. Neutrons and electrons also form an atom.
For b. The element is oxygen which is a non-metal and will form a negative ion while forming ionic bond.
<u>Explanation:</u>
There are 3 subatomic particles which form an atom. These are neutrons, protons and electrons.
Neutrons carry no charge, protons carry positive charge and electrons carry negative charge. Neutrons and protons are present in nucleus and electrons revolve around the nucleus.
The energy which is present between neutrons and protons are nuclear energy and the energy which is present between electrons and protons are electrostatic energy.
In an element, number of protons is always equal to the number of electrons. The atomic number is equal to the number of protons or electrons. The element which has atomic number 8 is Oxygen.
The electronic configuration of this element is 
This element requires only 2 electrons to form a stable electronic configuration. An element which gains electron is considered as a non-metal and forms a negative ion because number of electrons increases.
Limestone, yeah limestone.