A hydrocarbon of unknown structure has the formula C8H10. On catalytic hydrogenation over the Lindlar catalyst, 1 equivalent of hydrogen is absorbed. On hydrogenation over a palladium catalyst, 3 equivalents of H2 are absorbed. a) The degrees of unsaturation in the unknown is(are) ___ b) The number of triple bonds is ___ c) The number of double bonds is ___ d) The number of rings is ___

(a). 4

(b). 1 triple bond.

(c). 1

(d). 1 ring.

Explanation:

Without mincing words let's get started. So, we have that the chemical formula for the compound is C8H10. So, we are given from the question that lindlar's catalysts which is represented by H2 / Pd / CaCO3 and used in hydrogenation especially from alkyne to alkene.

(a). The degrees of unsaturation in the unknown can be calculated as;

[ (2 × Number of carbon atoms) + (2 ) - (number of Nitrogen atoms) - (number of hydrogen atoms) - number of halogens) ÷ 2

= [(2 × 8) + 2 - 0 - 10 - 0 ] ÷ 2.

=( 16 + 2 -10 ) ÷ 2.

= ( 18 - 10) ÷ 2 = 8/2 = 4.

(b). The number of triple bonds is 1 because we are given from the question that "On catalytic hydrogenation over the Lindlar catalyst, 1 equivalent of hydrogen is absorbed" and this is the work of the catalyst to prevent the alkyne from going to alkane straight.

(c). The number of double bonds is 1 because we are given from the question that "On hydrogenation over a palladium catalyst, 3 equivalents of H2 are absorbed".

(d)The number of rings is 1

i believe the answer is a.