The only food that provides all the nutrients that humans need is human milk," Hattner said. "Mother's milk is a complete food. We may add some solid foods to an infant's diet in the first year of life to provide more iron and other nutrients, but there is a little bit of everything in human milk.
Because Air itself is not an element. it is made up by different elements such as Oxygen and nitrogen. since its made up of a mix of different elements, its rather a homogeneous mixture :)
Answer:- 0.800 moles of the gas were collected.
Solution:- Volume, temperature and pressure is given for the gas and asks to calculate the moles of the gas.
It is an ideal gas law based problem. Ideal gas law equation is used to solve this. The equation is:
PV=nRT
Since it asks to calculate the moles that is n, so let's rearrange this for n:

V = 19.4 L
T = 17 + 273 = 290 K
P = 746 mmHg
we need to convert the pressure from mmHg to atm and for this we divide by 760 since, 1 atm = 760 mmHg

P = 0.982 atm
R = 
Let's plug in the values in the equation to get the moles.

n = 0.800 moles
So, 0.800 moles of the gas were collected.