Ethanal is commerically prepared by one step oxidation of ethene in the presence of ionic catalyst in aqueous medium with an yield of $${\text{90% }}{\text{.}}$$
\[\text{C}{{\text{H}}_{2}}=C{{H}_{2}}+{{O}_{2}}\xrightarrow[\begin{smallmatrix}
Pb(II)|Cu(II) \\
\text{(in water)}
\end{smallmatrix}]{\text{Catalyst}}C{{H}_{3}}CHO\]
84.
Increased level of greenhouse gases causes global warming which will result in
88.
Which of the following practices involve green chemistry?
(i) Substitute $$CFCs$$ by environmental friendly $$HFCs$$ and other compounds.
(ii) Replace halogenated solvent by liquid $$C{O_2}$$ for drycleaning.
(iii) Use of $${H_2}{O_2}$$ for bleaching instead of $$C{l_2}.$$
$$HFCs$$ are considered to be more friendly to environment. Use of tetrachloroethene as a solvent in dry cleaning industry has been replaced by liquefied $$C{O_2}$$ along with a suitable detergent which is less harmful. For bleaching of clothes in the laundry $${H_2}{O_2}$$ is being used instead of $$C{l_2}$$ which give better results, is not harmful and saves a lot of water.
Phosphate pollution is caused by sewage and agricultural fertilizers.
90.
The irritant red haze in the traffic and congested places is due to presence of which of the following ?
(i) Oxides of sulphur
(ii) Oxides of nitrogen
(iii) Carbon dioxide
(iv) Mists, smoke and dust
(v) Smog