A diatomic molecule X₂ has a body-centred cubic (bcc) structure with a cell edge of 300 pm. The density of the molecule is 6.17 g cm^–3. The number of molecules present in 200 g of X₂ is :
(Avogadro constant (N _A) = 6 $$ \times $$ 10²³ mol^–1 )

The minimum number of moles of O₂ required for complete combustion of 1 mole of propane and 2 moles of butane is _____.

The number of chiral carbon(s) present in
peptide, Ile-Arg-Pro, is _____.

A soft drink was bottled with a partial pressure of CO₂ of 3 bar over the liquid at room temperature. The partial pressure of CO₂ over the solution approaches a value of 30 bar when 44 g of CO₂ is dissolved in 1 kg of water at room temperature. The approximate pH of the soft drink is ______ $$ \times $$ 10^–1.
(First dissociation constant of
H₂CO₃ = 4.0 $$ \times $$ 10^–7; log 2 = 0.3; density
of the soft drink = 1 g mL^–1) .