Answer:
Atoms are single neutral particles. Molecules are neutral particles made of two or more atoms bonded together.
Explanation:
Atom refers to the smallest constituent unit of a chemical element. Molecules refer to a group of two or more atoms that are held together due to chemical bonds.
Answer : The correct option is, (D) 3600 kJ
Explanation :
Mass of octane = 75 g
Molar mass of octane = 114.23 g/mole
Enthalpy of combustion = -5500 kJ/mol
First we have to calculate the moles of octane.

Now we have to calculate the heat released in the reaction.
As, 1 mole of octane released heat = -5500 kJ
So, 0.656 mole of octane released heat = 0.656 × (-5500 kJ)
= -3608 kJ
≈ -3600 kJ
Therefore, the heat released in the reaction is 3600 kJ
D. Protons, Atomic number is the number of protons in an atom.
Answer:
The atomic number is the number of protons in the nucleus