The flocculation value of HCl for arsenic sulphide sol.
is 30 m mol L^-1 If H₂SO₄ is used for the flocculatiopn of arsenic sulphide, the amount in grams, of H₂SO₄ in 250 ml required for the above purposed is ______.
(molecular mass of H₂SO₄ = 98 g/mol)

3 g of acetic acid is added to 250 mL of 0.1 M HCL and the solution made up to 500 mL. To 20 mL of this solutions $${1 \over 2}$$ mL of 5 M NaOH is added. The pH of the solution is __________.

[Given : pKa of acetic acid = 4.75, molar mass of acetic of acid = 60 g/mol, log 3 = 0.4771] Neglect any changes in volume.

The standard heat of formation $$\left( {{\Delta _f}H_{298}^0} \right)$$ of ethane (in kj/mol), if the heat of combustion of ethane, hydrogen and graphite are - 1560, -393.5 and -286 Kj/mol, respectively is :

Consider the following reactions :

$$NaCl{\rm{ }} + {\rm{ }}{K_2}C{r_2}{O_7} + \mathop {{H_2}S{O_4}}\limits_{(conc.)} $$$$ \to $$ (A) + side products

(A) + NaOH $$ \to $$ (B) + Side products

$$\left( B \right){\rm{ }} + \mathop {{H_2}S{O_4}}\limits_{(dilute)} + {\rm{ }}{H_2}{O_2}$$ $$ \to $$ (C) + Side products

The sum of the total number of atoms in one molecule each of (A) and (B) and (C) is