Using ideal gas equation,

Here,
P denotes pressure
V denotes volume
n denotes number of moles of gas
R denotes gas constant
T denotes temperature
The values at STP will be:
P=1 atm
T=25 C+273 K =298.15K
V=663 ml=0.663L
R=0.0821 atm L mol ⁻¹
Mass of gas given=1.25 g g
Molar mass of gas given=?


Putting all the values in the above equation,

Molar mass of the gas=46.15
<span>q(rxn) = - [q(water)+q(bomb)]
q(rxn) = -{[ (1000g)(4.184)(5.0)] + [ (5.0)(0.10)]}
q(rxn) = - (20920 + 0.5)
Now we divide 3.5g
q(rxn)= - (20920)/(3.5g)
q(rxn) = 5977.14
And final answer, change is to Kilo joule unit
-q(rxn) = 5.23 KJ/unit</span>
The answer is (1) CaCO3. The bond between C and O is covalent bond. And the bond between Ca2+ and CO3 2- ion is the ionic bond. So the compound CaCO3 satisfy this condition.