Look at the four chemical reactions. Reaction 1: 2H2 + O2 → 2H2O Reaction 2: 2NaCl → 2Na + Cl2 Reaction 3: CaO + H2O → Ca(OH)2 Reaction 4: 4Fe + 3O2 → 2Fe2O3 Which statement identifies the reaction that is different from the rest and explains correctly why it is different? (1 point) Reaction 2, because a single reactant is decomposed Reaction 1, because two reactants have decomposed Reaction 2, because a single ion is replaced in a compound Reaction 1, because two ions have interchanged their positions

reaction 1, because a single product is formed.

Explanation: I took the test and got it right.

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.