Which one of the following statements is correct? from Chemistry

Subject

Chemistry

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

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


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


A.

Ferromagnetic substance like ZnFe2O4 becomes paramagnetic on heating

Among all the given options, option a is the correct one. Ferromagnetic substances such as ZnFe2O4 becomes paramagnetic on heating.


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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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