That's a nice souvenir, I ... it!
a) going to buy
b) am buying
c) will buy

If she ... enough money she'd go on holoday
a) has
b) had
c) would have

If I go to Paris, I ... the Eiffen
a) visit
b) will wisit
c) would visit

... River Thames is in London
a) a
b) the
c) -

If you ... ice in wter it floats
a) will drop
b) would drop
c) drop

That's a nice souvenir, I ... it!

c) will buy  (спонтанное решение)

If she ... enough money she'd go on holiday.

b) had  (условное 2 типа - нереальное событие, относящееся к наст. вр.)

If I go to Paris, I ... the Eiffel Tower.

b) will wisit  (условное 1 типа - возможное условие и вполне вероятный результат)

... River Thames is in London

b) the  (названия рек употребляются с опред. артиклем)

If you ... ice in water, it floats.

c) drop (условное нулевого типа для выражения общеизвестной истины)