B) 40%
The balanced equation indicates that for every 3 moles of H2 used, 2 moles of NH3 will be produced. So the reaction if it had 100% yield would produce (2.00 / 3) * 2 = 1.333333333 moles of NH3. But only 0.54 moles were produced. So the percent yield is 0.54 / 1.3333 = 0.405 = 40.5%. This is a close enough match to option "b" to be considered correct.
Answer:
Period and groups are different because
PERIODS are the number of shells
I.e in lame man words the no of circles when drawn an element
GROUPS : these are the number of electrons in the outermost shell
Groups determine the valency*
