A solution contains Na 2​ CO 3​ and NaHCO 3​ . 10 mL of the solution required 2.5 mL of 0.1 M H 2​ SO 4​ for neutralisation using phenolphthalein as indicator. Methyl orange is then added when a further 2.5 mL of 0.2 M H 2​ SO 4​ was required. Calculate the amount of Na 2​ CO 3​ and NaHCO 3​ in one litre of the solution.

100mL of a water sample contains 0.81g of calcium bicarbonate and 0.73 of magnesium bicarbonate. The hardness of this water sample expressed in terms of equivalents of CaCO 3​ is:(molar mass of calcium bicarbonate is 162g mol^−1 and magnesium bicarbonate is 146 gmol −1 )

(A) 1000 ppm

(B) 10000 ppm

(C) 100 ppm

(D) 5000 ppm

Solution :

neq​.CaCO3​=neq​Ca(HCO3​)2​+neq​Mg(HCO3​)2​

or 

(W​÷100) ×2 = (0.81​÷ 162)×2 + (0.73÷146)​×2 

∴w=1.0

∴ Hardness=(1.0÷100) ×10^6=10000ppm

Hence correct option is (B) 10000ppm

25 gm of an unknown hydrocarbon upon burning produce 88 gm of CO2 and 9 gm of H2O. this unknown hydrocarbon contains.

(A ) 18g of carbon and 7g of hydrogen

(B) 20g of carbon and 5g of hydrogen

(C) 22g of carbon and 3g of hydrogen

(D) 24 g of carbon and 1g of hydrogen

Solution: