Premise:
"With 90% of the population professing to be Hindus, Nepal claims to be the only officially Hindu nation on earth."
Hypothesis: Hindus from all over the world emigrate to Nepal.

it is not possible to tell

Premise:
"This 1770s mansion was formerly the residence of viscount Powerscourt and still possesses some magnificent plasterwork, particularly in the rear exit hall."
Hypothesis: Viscount Powerscourt This mansion used to reside in this mansion.

yes

Premise:
"For expensive items, say a carpet or a leather jacket, the process might be lengthy and involve several glasses of tea and a good half hour of your time."
Hypothesis: Carpets are more expensive than leather jackets.
it is not possible to tell