Question

The amount of zinc (atomic weight = 65) necessary
to produce 224 ml of H, by the reaction with an
acid will be
(1) 6.5 gm
(2) 0.065 gm
(3) 7.5 gm
(4) 0.65 gm​

Answer 1

0.224l of h2 is produced at stp

so moles of h2 will be  0.224/22.4 = 0.01 moles

Zn + 2H(+) ---> Zn(2+) + H2.

from this we can understand 1 mole of zn gives one mole of h2

so no of moles of zn is 0.01

amount of zn = 65*0.01

=0.65 g that is option4