Use the periodic table to determine which of the following could be an isotope of indium (in). check all that apply. z = 49, a = 113 n = 64, z = 49 n = 61, a = 113 a = 110, n = 49

The isotopes are the elements with same atomic number but different atomic mass or mass number

The mass number is denoted by Z

The mass number is denoted by A

The number of neutrons = N

We know that for an element

A = Z + N

As given the element is indium , its atomic number = Z = 49

Z = 49, A = 113 N = 64,  This could be an isotope of indium

Z = 49 N = 61, A = 113 , this could also be an isotope of indium

A = 110, N = 49 it means Z = Z - N = 110-49 = 61 So this is not isotope of indium

n2(g) + 3h2-> 2nh3(g)   this is the balanced equation

note the mole ratio between n2, h2 and nh3.   it is 1 : 3 : 2   this will be important.

moles n2 present = 28.0 g n2 x 1 mole n2/28 g = 1 mole n2 present

moles h2 present = 25.0 g h2 x 1 mole h2/2 g = 12.5 moles h2 present

based on mole ratio, n2 is limiting in this situation because there is more than enough h2 but not enough n2.

moles nh3 that can be produced = 1 mole n2 x 2 moles nh3/mole n2 = 2 moles nh3 can be produced

grams of nh3 that can be produced = 2 moles nh3 x 17 g/mole = 34 grams of nh3 can be produced

note:   the key to this problem is recognizing that n2 is limiting, and therefore limits how much nh3 can be produced.