Electrostatics i think thats the right answer
A) 2H₂(g) + O₂(g) → 2H₂O(l) + 285.83 kJ
Exothermic
B) 2Mg + O₂ → 2MgO + 1200kJ
Exothermic
Answer: polar,non polar
Explanation:
The electronegativity of C is 2.5 and of O is 3.5 .The difference in electronegativity(3.5-2.5=1.0) is 1.0 and as per rule if the difference in electronegativity of atoms in a bond is >0.4 then the bond is considered polar. So in this case C-O bond is polar.
However, the symmetrical arrangement of the bonds in the molecule of CO2 makes its non polar.The CO2 molecule is linear so the C-O dipole moment on either side will cancel out each other hence the net dipole moment will be zero.
Via the half-life equation we have:

Where A is the amount initially and final amount after some time has passed, t is the time elapsed, h is the half life time and so:

Therefore there will be 2.8125 grams left after 140 seconds.