Which of the following represents the Lewis structure of N₂ molecule?

The decomposition of a certain mass of CaCO₃ gave 11.2 dm³ of CO₂ gas at STP. The mass of KOH required to completely neutralise the gas is :

• 56 g

• 28 g

• 42 g

• 20 g

The density of a gas is 1.964 g dm^-3 at 273 K and 76 cm Hg. The gas is :

• CH₄

• C₂H₆

• CO₂

• Xe

4.

0.06 mole of KNO₃ solid is added to 100 cm³ of water at 298K. The enthalpy of KNO₃ aqueous solution is 35.8 kJ mol^-1. After the solute is dissolved the temperature of the solution will be:

• 293 K

• 298 K

• 301 K

• 304 K

4 moles each of SO₂ and O₂ gases are allowed to react to form SO₃, in a closed vessel. At equilibrium 25% of O₂ is used up. The total number of moles of all the gases at equilibrium is :

• 6.5

• 7.0

• 8.0

• 2.0

ΔG° vs T plot in the Ellingham's diagram slopes upwards for the reactions:

• Mg+ 1/2O₂ → MgO

• 2Ag + 1/2O₂ → Ag₂O

• C + 1/2O₂ → CO

• CO + 1/2O₂ → CO₂

Which of the following has the highest bond order?

• N₂

• O₂

• He₂

• H₂

Which of the following is diamagnetic?

• H${}_2^{+}$

• O₂

• Li₂

• He${}_2^{+}$

Solubility product of a salt AB is 1 x 10^-8 M² in a solution in which the concentration of A⁺ ions is 10M.The salt will precipitate when the concentration of B ions is kept :

• between 10^-8 M to 10^-7 M

• between 10^-7 M to 10^-8 M

• >10^-5 M

• <10^-8 M

The pH of 10^-8 M HCl solution is:

• 8

• more than 8

• between 6 and 7

• slightly more than 7