19 g of a mixture containing NaHCO₃ and Na₂CO₃ on complete heating liberated 1.12 L of CO₂ at STP. The weight of the remaining solid was 15.9 g. What is the weight (in g) of Na₂CO₃ in the mixture before heating?

• 8.4

• 15.9

• 4.0

• 10.6

Under which one of the following conditions do real gases approach the ideal gas behaviour?

• Low temperature and high pressure

• High temperature and high pressure

• High temperature and low pressure

• Low temperature and low pressure

13.

Which one of the following is the ratio of the lowering of vapour pressure of 0.1 M , aqueous solutions of BaCl₂, NaCl and Al₂SO₃ respectively?

• 3 : 2 : 5

• 5 : 2 : 3

• 5 : 3 : 2

• 2 : 3 : 5

Which one of the following exhibits enantiomerism?

• BeCH₂-CH₂-CH₂-CH₂Br

• H₃C-CH(Br)-CH₂-CH₂-CH₃

• H₃C-CH₂-CH₂-CH₂Br

• H₃C-CH₂-CBr₂-CH₃

Nitrobenzene on reduction using zinc in alkaline medium results in X. The number of sigma (σ) and pi ($\mathrm{\pi }$) bonds in X is-

• 24 σ, 7 $\mathrm{\pi }$

• 24 σ, 6 

• 27 σ, 7 

• 24 σ, 6 

Which property among the following is same for both hydrogen and deuterium molecules?

• Bond energy

• Melting point

• Boiling point

• Bond length

In which of the following reactions hydrogen is not liberated?

• Reaction of fused NaOH with C

• Reaction of NaOH with sulphur

• Heating the concentrated NaOH with Si

• Reaction of zinc with NaOH

Which one of the following statements is not correct?

• Moissan boron is amorphous

• The reaction between boron and concentrated HNO₃, gives N₂O.

• Amorphous boron on heating with oxygen forms B₂O₃.

• Boron is a non-conductor of electricity.

Which one of the following is a correct set?

• Diamond, sp²

• Graphite, sp³

• Diamond, sp

• Graphite, sp²

Which air pollutant is responsible for Bhopal gas tragedy?

• PIC

• CFC

• MIC

• CO