The volume of neon gas in cm³ at STP having the same number of atoms as that present in 800 mg of Ca is (At. mass : Ca = 40 g mol^-1, Ne = 20 g mol^-1)

• 448

• 896

• 224

• 112

The ionisation enthalpy of He⁺ ion is 19.60 10^-18 J atom^-1. The ionisation enthalpy of Li²⁺ ion will be

• 84.2 × 10^-18 J atom^-1

• 44.10 × 10^-18 J atom^-1

• 63.20 × 10^-18 J atom^-1

• 21.20 × 10^-18 J atom^-1

3.

How many molecules of CO₂ are formed when one milligram of 100% pure CaCO₃ is treated with excess hydrochloric acid?

• 6.023 × 10²³

• 6.023 × 10¹⁸

• 6.023 × 10²¹

• 6.023 × 10²²

Molecular shapes of SF₄ ,CF₄ and XeF₄ and the number of lone pairs on the central atom are respectively

• the same, with 1, 2 and 1

• the same with 1, 0 and 1

• different with 0, 1 and 2

• different with 1, 0 and 2

Which one of the following is not correct in respect of hybridization of orbitals?

• The orbitals present in the valence shell are hybridized

• The orbitals undergoing hybridization have akmost equal energy

• Pure atomic orbitals are more effective in forming stable bonds than hybrid orbitals

• It is not always that only partially filled orbitals participate in hybridization in some cases even filled orbitals in valence shell take part.

Allyl cyanide molecule contains

• 9 sigma bonds, 4 pi bonds and no lone pair

• 9 sigma bonds, 3 pi bonds and one lone pair

• 8 sigma bonds, 5 pi bonds and one lone pair

• 8 sigma bonds, 3 pi bonds and two lone pairs

Two vessels of volumes 16.4 L and 5 L contains two ideal gases of molecular existence at the respective temperature of 27°C and 227°C and exert 1.5 and 4.1 atm, respectively. The ratio of the number of molecules of the former to that of the later is

• 2

• 1

• $\frac{1}{2}$

• $\frac{1}{3}$

When 4 g of an ideal gas A is introduced into an evacuated flask kept at 25°C, the pressure is found to be one atmosphere. If 6 g of another ideal gas B is then added to the same flask, the pressure becomes 2 atm at the same temperature. The ratio of molecular weight (M_A : M_B) of the two gases would be

• 1 : 2

• 2 : 1

• 2 : 3

• 3 : 2

Which one of the following statements is correct?

• Ferromagnetic substance like ZnFe₂O₄ becomes paramagnetic on heating

• NaCl is a paramagentic salt

• CuSO₄ is a diamagnetic salt

• MnO is an example of antiferronmagnetic substance

Among the elements B, Mg, Al and K the correct order of increasing metallic character is

• B < Al < Mg < K

• B < Mg < Al < K

• Mg < B < Al < K

• Mg < Al < B < K