Four gas cylinders containing He, N2, CO2 and NH3 gases separately are gradually cooled from a temperature of 500 K. Which gas will liquify first?
(Given Tc in K $$-$$ He : 5.3, N2 : 126, CO2 : 304.1 and NH3 : 405.5)
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : The metal carbon bond in metal carbonyls possesses both $$\sigma$$ and $$\pi$$ character.
Reason (R) : The ligand to metal bond is a $$\pi$$ bond and metal to ligand bond is a $$\sigma$$ bond.
In the light of the above statements, choose the most appropriate answer from the options given below.
Match List-I with List-II :
List-I |
List-II |
||
---|---|---|---|
(a) | Biochemical oxygen demand | (i) | oxidising mixture |
(b) | Photochemical smog | (ii) | polar stratospheric cloud |
(c) | Classical smog | (iii) | organic matter in water |
(d) | Ozone layer depletion | (iv) | reducing mixture |
Choose the correct answer from the options given below :
Which of the following is the most stable carbocation?