The number of molecules with energy greater than the threshold energy for a reaction increases five fold by a rise of temperature from 27^oC to 42^oC. Its energy of activation in J/mol is _____.
(Take ln 5 = 1.6094; R = 8.314 J mol^–1 K^–1)

The osmotic pressure of a solution of NaCl is 0.10 atm and that of a glucose solution is 0.20 atm. The osmotic pressure of a solution formed by mixing 1 L of the sodium chloride solution with 2 L of
the glucose solution is x $$ \times $$ 10^–3 atm. x is _____. (nearest integer)

A 100 mL solution was made by adding 1.43 g of Na₂CO₃.xH₂O. The normality of the solution is 0.1 N. The value of x is _____.

(The atomic mass of Na is 23 g/mol)

If a and b are real numbers such that
$${\left( {2 + \alpha } \right)^4} = a + b\alpha $$
where $$\alpha = {{ - 1 + i\sqrt 3 } \over 2}$$ then a + b is equal to :