Multiple Choice QuestionsWhich of the following pairs of compounds cannot exist together?
NaHCO3 and NaCl
NaHCO3 and NaOH
NaHCO3 and Na2CO3
Na2CO3 and NaOH
On dissolving a non-volatile solute in a solvent, the vapour pressure of the solvent is decreased by 10 mm of mercury. The mole fraction of the solute in this solution is 0.2. If the vapour pressure of the solvent is decreased by 20 mm of mercury by dissolving more solute, what is the mole fraction of solvent in this solution now?
0.2
0.4
0.6
0.8
Which of the following statements about ionic crystals is false?
Melting and boiling temperature of ionic crystals are very high
These are soluble in water and other solvent
At low temperature in sold state they are good conductor of electricity.
They have high cohesive energy
8.0 g of a radioactive substance remains 0.5 g in 1 h. What is its half-life period?
10min
15min
30min
None of these
The electronic configuration of an element is 1s2,2s2 2p6, 3s2 3p6, 3d10, 4s2 4p3. To which of the following elements it is similar in properties?
Boron
Oxygen
Nitrogen
Chlorine
Blister copper is melted in a furnace then stirred with green wooden logs. The purpose is
to expel the soluble gases out of the blister copper
to bring the impurities on the surface to oxidise them
to increase the carbon in copper
to reduce the metallic oxide impurities by the hydrocarbon gases coming out of the log during the process
During smelting of an ore an additional substance is added to make the impurities fusible. The name of it is
Slag
mud
gangue
flux
1.0 L of 2.0 M acetic acid is mixed with 1.0 L of 3.0 Methyl alcohol. The reaction is CH3COOH + C2H5OH CH2COOC2H5 + H2O. 1.0 L of 2.0 M acetic acid is mixed with 1.0 L of 3.0 Methyl alcohol. The reaction is
0.5 times
2.0 times
4.0 times
0.25 times
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