The volume of neon gas in cm3 at STP having the same number of at

Subject

Chemistry

Class

JEE Class 12

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1.

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


A.

448

Mass of Ca = 800 mg = 8001000 = 0.8 gm

Moles of Ca in 0.8 gm = 0.8 40 = 2 × 10-2

At STP, volume of 1 mole = 22400 cm3

 At STP, volume of 2 × 10-2 moles

 = 22400 × 2 × 10-2

 = 448 cm3


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2.

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


4.

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


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5.

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.


6.

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


7.

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

  • 12

  • 13


8.

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: MB) of the two gases would be

  • 1 : 2

  • 2 : 1

  • 2 : 3

  • 3 : 2


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9.

Which one of the following statements is correct?

  • Ferromagnetic substance like ZnFe2O4 becomes paramagnetic on heating

  • NaCl is a paramagentic salt

  • CuSOis a diamagnetic salt

  • MnO is an example of antiferronmagnetic substance


10.

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


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