Explanation:
21. The given molecule for cracking is tetradecane.
On cracking it forms one mole of decane (C10H22) and two moles of ethene gas.
The chemical equation is shown below:

22. The essential condition for the formation of an ester is the reaction of alcohol and acid in presence of concentrated sulfuric acid.
Thus among the given options, the first option is the correct one.
23. Isomers of butanol are shown below:
It is 2-butanol.
The position of -OH group changes to the second carbon.
Among the choices, bromine exists as liquid under standard temperature and pressure conditions. Unlike other diatomic molecules which exist as gases, due to its heavy molecular weight, it exists as solid. Francium and cesium are solids while iodine is gas.Answer is 1.
1.77 so A. I don’t need to explain this just helping out haha