The statement that is not correct is

• A furnace filled with haemalite is used to convert cast iron to wrought iron

• Collectors enhance the wettability of mineral particles during froth flotation

• In vapour phase refining, metal should form a volatile compound

• Copper from its low grade ores is extracted by hydrometallurgy

For Cr₂O${}_7^{2-}$ + 14 H⁺ + 6e^- → 2Cr³⁺ + 7H₂O; E° = 1.33 V. At [Cr₂O${}_7^{2-}$] = 4.5 millimole, [Cr³⁺] = 15 millimole, E is 1.067 V. The pH of the solution is nearly equal to

• 2

• 3

• 5

• 4

1.78 g of an optically active L-amino acid (A) is treated with NaNO₃/ HCl at 0°C. 448 cm³ of nitrogen was at STP is evolved. A sample of protein has 0.25% of this amino acid by mass. The molar mass of the protein is

• 36500 g mol^-1

• 34500 g mol^-1

• 35400 g mol^-1

• 35600 g mol^-1

10 g of a mixture of BaO and CaO requires 100 cm³ of 2.5 M HCl to react completely. The percentage of calcium oxide in the mixture is approximately (Given: molar mass of BaO = 158)

• 52.6

• 55.1

• 44.9

• 47.4

The ratio of heats liberated at 298 K from the combustion of one kg of coke and by burning water gas obtained from kg of coke is (Assume coke to be 100% carbon). (Given : enthalpies of combustion of CO₂, CO and H₂ as 393.5 kJ, 285 kJ, 285 kJ respectively all at 298 K)

• 0.79 : 1

• 0.69 : 1

• 0.86 : 1

• 0.96 : 1

Impure copper containing Fe, Au, Ag as impurities is electrolytically refined. A current of 140 A for 482.5 s decreased the mass of the anode by 22.26 g and increased the mass of cathode by 22.011 g. Percentage of iron in impure copper is (Given molar mass Fe = 55.5 g mol^-1, molar mass Cu = 63.54 g mol^-1)

• 0.95

• 0.85

• 0.96=7

• 0.90

25 cm³ of oxalic acid completely neutralised 0.064 g of sodium hydroxide. Molarity of the oxalic acid solution is

• 0.064

• 0.045

• 0.015

• 0.032

The statement that is not correct is

• Angular quantum number signifies the shape of the orbital

• Energies of stationary states in hydrogen like atoms is inversely proportional to the square of the principal quantum number

• Total number of nodes for 3s-orbital is three

• The radius of the first orbit of He is half that of the first orbit of hydrogen atom

For the equilibrium,

CaCO₃ (s) $\rightleftharpoons$ CaO (s) + CO₂ (g) ; 

K_p = 1.64 atm at 1000 K

50 g of CaCO₃ in a 10 L closed vessel is heated to 1000 K. Percentage of CaCO₃ that remains unreacted at equilibrium is (Given, R = 0.082 L atm K^-1 mol^-1).

• 40

• 50

• 60

• 20

Density of carbon monoxide is maximum at

• 2 atm and 600 K

• 0.5 atm and 273 K

• 6 atm and 1092 K

• 4 atm and 500 K