20.0 g of a magnesium carbonate sample decomposes on heating to

Subject

Chemistry

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

1.

A gas such as carbon monoxide would be most likely to obey the ideal gas law at

  • high temperatures and low pressures

  • low temperatures and high pressures

  • high temperatures and high pressures

  • high temperatures and high pressures

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2.

If Avogadro number NA, changed from 6.022 x 1023 mol-1 this would change

  • the definition of mass in units of grams

  • the mass of one mole of carbon

  • the ratio of chemical species to each other in the balanced equation

  • the ratio of chemical species to each other in the balanced equation

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3.

What is the pH of the resulting solution when equal volumes of 0.1 M NaOH and 0.01 M HCl are mixed?

  • 12.65

  • 2.0

  • 7.0

  • 7.0

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4.

Decreasing order of stability of straight O subscript 2 comma space straight O subscript 2 superscript minus comma space straight O subscript 2 superscript plus comma space and space straight O subscript 2 superscript 2 minus end superscript is

  • straight O subscript 2 superscript plus space greater than space straight O subscript 2 space greater than space straight O subscript 2 superscript minus space greater than space straight O subscript 2 superscript 2 minus end superscript
  • straight O subscript 2 superscript 2 minus end superscript space greater than space straight O subscript 2 superscript minus space greater than space straight O subscript 2 space greater than space straight O subscript 2 superscript plus
  • straight O subscript 2 space greater than straight O subscript 2 superscript plus space greater than space straight O subscript 2 superscript 2 minus end superscript space greater than thin space straight O subscript 2 superscript minus
  • straight O subscript 2 space greater than straight O subscript 2 superscript plus space greater than space straight O subscript 2 superscript 2 minus end superscript space greater than thin space straight O subscript 2 superscript minus
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5.

Which one of the following pairs of the solution is not an acidic buffer?

  • HClO4 and NaClO4

  • CH3COOH and CH3COONa

  • H2CO3 and Na2PO4

  • H2CO3 and Na2PO4

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6.

20.0 g of a magnesium carbonate sample decomposes on heating to give carbon dioxide and 8.0 g magnesium oxide. What will be the percentage purity of magnesium carbonate in the sample? (Atomic weight of Mg =24)

  • 75

  • 96

  • 60

  • 60


D.

60

In the given problem we have a practical yield of MgO. For calculation of percentage yield of MgO. we need a therortical yield of MgO. For this, we shall use mole concept.

MgCO3(s) → MgO (s) + CO2(g)  .. (i)


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7.

The heat of combustion of carbon to CO2 is -395.5 kJ/mol. The heat released upon the formation of 35.2 g CO2 from carbon and oxygen gas is 

  • -315 kJ

  • +315 kJ

  • -630 kJ

  • -630 kJ

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8.

The formation of the oxide ion O2- (g), from oxygen atom requires first an exothermic and then an endothermic step as shown below,

straight O space left parenthesis straight g right parenthesis space plus space straight e to the power of minus space rightwards arrow space straight O to the power of minus left parenthesis straight g right parenthesis semicolon space increment subscript straight f straight H to the power of straight o space equals space minus 141 space kJ space mol to the power of negative 1 end exponent
straight O to the power of minus space left parenthesis straight g right parenthesis space plus straight e to the power of minus space rightwards arrow space straight O to the power of 2 minus end exponent space left parenthesis straight g right parenthesis semicolon space increment subscript straight f straight H to the power of straight o space equals plus 780 space kJ space mol to the power of negative 1 end exponent
Thus, the process of formation of O2- in the gas phase is unfavourable even though O2- is isoelectronic with neon. It is due to the fact that

  • electron repulsion outweighs the stability gained by achieving a noble gas configuration

  • O- ion has comparatively smaller size that oxygen atom

  • oxygen is more electronegative

  • oxygen is more electronegative

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9.

What is the mass of precipitate formed when 50 mL of 16.9% solution of AgNO3 is mixed with 50 mL of 5.8% NaCl solution?

(Ag = 107.8, N = 14, O = 16, Na = 23, Cl = 35.5)


  • 28 g

  • 3.5 g 

  • 7 g 

  • 7 g 

1927 Views

10.

Which is the correct order of increasing energy of the listed orbitals in the atom of titanium?

  • 3s 4s 3p 3d

  • 4s 3s 3p 3d

  • 3s 3p 3d 4s

  • 3s 3p 3d 4s

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