What’s the element of the picture shown?

Hydrogen

Explanation:

I am assuming the two circles in the middle are the proton and neutron.  If so, you only have 1 proton.  On the periodic table, the periodic table with only 1 proton is hydrogen.

You can tell how many protons an element has by looking at its atomic mass.  Hydrogen has an atomic mass of 1.

Answer is (2) - hydrogen carbonate

Explanation:

NaHCO₃ is an ionic compound which is made from Na⁺ and HCO₃⁻ ions. The decomposition is

NaHCO₃ → Na⁺ + HCO₃⁻

Among the resulted ions, Na⁺ is a monatomic ion while HCO₃⁻ is a polyatomic ion.

Polyatomic ions mean ions which are made of two or more different atoms.

HCO₃⁻ is made from 3 atoms as H, C and O. The name of HCO₃⁻ ion is bicarbonate or hydrogen carbonate.