Answer:
The filter bed is cleaned by occasional backwashing ;-; im sorry if this isn't a great answer but I tried
Answer: balanced chemical equation: 
Net ionic equation :
Explanation:
A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
The balanced chemical equation is:

Spectator ions are defined as the ions which does not get involved in a chemical equation or they are ions which are found on both the sides of the chemical reaction present in ionic form.
The ions which are present on both the sides of the equation are sodium and nitrate ions and hence are not involved in net ionic equation.
Hence, the net ionic equation is
The valence electrons are the parts of an atom that make interactions and make chemical bonds.
Every atom is made of three different components, a positively charged proton, neutrally charged neutron and negatively charged electron. The protons and the neutrons make up the atom's core and the electrons orbit around that core.
The electrons that orbit around the atom's core in its outer-most orbit (the one that is the furthest from the atom's core) can interact with electrons of other atoms, forming different kinds of chemical bonds.
If there is an exchange of the electrons (one atom donates its electrons to another atom), that results in forming of ions, then those two atoms can be linked in an ionic bond.
If an electron is shared between two atoms, then that bond is called a covalent bond.
Answer:
Rb2CO3(aq)+Fe(C2H3O2)2(aq)--> 2Rb(C2H3O2)(aq) + FeCO3(s)
Explanation:
The reaction shown in the answer is the reaction of rubidium carbonate and iron II acetate. Rubidium is far more reducing than Fe II hence it can displace Fe II from its salt as shown.
The reducing property of metals depends on the value of their individual electrode potential values. For rubidium, its standard reduction potential is -2.98 V while that of Fe II is -0.44V. Hence rubidium can displace Fe II from its salt as shown above.