Which of the following is correct order for heat of combustion?

The heat of combustion is

Give the decreasing order of the stability of the following or increasing order of heat of combustion. (I)

Give the decreasing order of the stability of the following or increasing order of heat of combustion. (I)

Which of the following order is correct for heat of hydrogenation of these compounds?

Which of the following statements is correct about heat of combustion?