The coefficients of the substances give you the ratio of the number of moles.
The 4 before the H2O and the 5 before the HCl tell you that for every 5 moles of HCl created, 4 moles of H2O had to react.
Therefore:

can be used to find the moles of H2O that react.
Explanation:
Hi! I don't know why I am not getting any brainliest answer and if you are kind enough could you please mark me as the brainliest answer and please follow me also.
Answer:

Explanation:
The concentration of CO2 in the room will be the amount of CO2 in the room at time t, divided by the volume of the room.
Let A(t) be the amount of CO2 in the room, in ft3 CO2.
The air entering the room is 3000 ft3/min with 0.06% concentrarion of CO2. That can be expressed as (3000*0.06/100)=1.8 ft3 CO2/min.
The mixture leaves at 3000 ft3/min but with concentration A(t)/V. We can express the amount of CO2 leaving the room at any time is A(t).
We can write this as a differential equation

We can rearrange and integrate

We also know that A(0) = 12000*(0.3/100)=36 ft3 CO2.

Then we have the amount A(t) as

Helium has an atomic number 2 and an atomic weight of 4 grams per mole. It is one of the noble gas (which means that it is stable) and also a nonmetal. Its electron configuration is 1s2. There are energy levels and they are s, p, d and f. The s level means that its maximum number of electrons is only 2.