Im not positive but i think it is When it is a gas?
Answer: Burning changes the chemical make up of an object.
Explanation:
A chemical change can be defined as a change in the substance when it combines with other kind of substance to form a new substance. A chemical change can also occur when a substance is broken down into two or more products. These changes cannot be reversed. These changes affect the physical make up of an object. For example, burning as when an object is burned it cannot be transformed into its original form. A wood if burned can be converted into ash, water and carbon dioxide cannot regain its original form after burning so burning brings about chemical change in an object.
Answer: A. Sun, Moon, Earth
Answer:
The decreasing order of bond length in the carbon - carbon bonds will be:

Explanation:
Bond length is defined as average distance between two nuclei of bonded atoms in a molecule.Bond length is inversely proportional to the number of bonds present between two atoms.
...[1]
Bond energy is defied as amount of energy required to break apart the bond of 1 mole of molecule into their individual atom. Bond energy is directly proportional to the number of bonds present between two atoms.
..[2]
From [1] and [2]:

hybridized
hybridized
hybridized
Extent of overlapping of orbitals in these hybridization;

Higher the overlapping of orbital more closer will be both atoms to each other and shorter will be the bond lenght.
So, the decreasing order of bond length in the carbon - carbon bonds will be:
