Answer:
Option D. The total amount of both matter and energy does not change.
Explanation:
From Law of conservation of energy and Einstein's mass-energy relation, we know that, energy neither is formed not is destroyed. It converts from one form to another. Einstein's mass-energy relation: E = mc². It means, Matter is a form of energy i.e. matter holds energy equivalent to product of its mass and square of speed of light. Matter and energy can change forms but the total amount does not change in a closed system. Thus, correct option is D.
<h2>Heptene formed is -</h2><h2>

</h2>
Explanation:
The two possibilities when the peroxide is not present
+ HBr →
In presence peroxide,
≡
+ HBr →
- When peroxides are present in the reaction mixture, hydrogen bromide adds to the triple bond of heptane with regioselectivity.
- This reaction is opposite to that of Markovnikov's rule which says that when asymmetrical alkene reacts with a protic acid HX, then the hydrogen of an acid is attached to the carbon with more in number of hydrogen substituents, and the halide (X) group is attached to the carbon with more in number of substituents of alkyl.
- One mole of HBr adds to one mole of 1-heptane.
- The structure of heptene formed is -

The usual units of density are g/cm.
You may have also seen g/mL used for density. Keep in mind that 1 cm = 1 mL.