This is how krypton appears in the periodic table. a purple box has k r at the center and 36 above. below it says krypton and below that 83.80.

rounded to the nearest whole number, how many protons are in an atom of krypton?

36
48
84
120

The number of protons in an atom of krypton is 36.

Explanation:

The number written above the symbol of Kr in the periodic table represents the atomic number of the element . Then the number written in the below represents the mass number.

So the mass number of krypton is 84 and the atomic number of krypton is 36. As it is known that number of protons and electrons will be equal in a stable element. Thus, the krypton atom will be having 36 protons.

step-by-step explanation:

whole numbers, zero or greater

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.