An acid solution was prepared by dissolving 0.767dm3 of hydrogen chloride gas in water at STP to make 0.25dm3 of solution.18cm3 of this solution were enough to neutralize 25cm3 containing 9.864g of the compound YHCO3 per liter of solution. Determine (i)Concentration of the base in g/dm3
(ii)Atomic mass of Y.
(iii)Write the correct formula of the base.

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.