The basic substances are called elements
Answer:
• The Na atom is formed when the Na+ ion gains an electron.
• A Na+ ion has 10 electrons and a Na atom has 11 electrons.
• A sodium atom has one more electron shell than a sodium ion.
• A Na+ ion is formed when a Na atom loses an electron
Answer:- Yes, strontum bromide and potassium sulfate gives a precipitate of strontium sulfate.
Explanations:- As per the solubility rules, all compounds of alkali metals are soluble.
Sulfate of most of the alkaline earth metals like Ca, Ba and Sr are insoluble.
A double displacement reaction takes place when strontium bromide and potassium sulfate are mixed and a precipitate of strontium sulfate is formed:

Note: (aq) stands for aqueous and (s) stands for solid and here it's precipitate.
Spring tides occur during the full moon and the new moon