Question

number of neutrons present in 1.7 gram of ammonia is

Answer 1

Here is your answer.

of moles of ammonia =1.7/17 =0.1mole.
No. of neutrons in one molecule of NH3 is 7 because H has no neutron.

Hope it helps you.

Answer 2

I mole of ammonia = 17g which contains
7 *6*10^23 neutrons
So,1.7 g contains = 4.2*10^23