Which important greenhouse gas,other than methane,is produced from agricultural fields?

Which of the following radioactive isotopes is used in the detection of thyroid cancer?

Two electrons occupying the same orbital are distinguished by

Ethanol when reacted with $PCl_5$ gives $A$,$POCl_3$ and $HCl$. $A$ reacts with silver nitrite to form $B$ (major product) and $AgCl$. $A$ and $B$ respectively are

Match column-$I$ with column-$II$ and choose the correct combination from the options given below.

Column-$I$	Column-$II$
$A$. National Botanical Research Institute	$I$. Carolus Linnaeus
$B$. Indian Botanical Garden	$II$. Taxon
$C$. Binomial Nomenclature	$III$. Howrah (India)
$D$. $A$ unit of Classification	$IV$. Lucknow

Let $A = \{1, 2, \{3, 4\}, 5\}$. Which of the following statements is incorrect and why?
${3, 4} \subset A$