A gas is a state of matter in, which atoms remains in a constant motion, they do not stick together. They are free and can move in all directions. The gas molecules expands to fill the available space. Hence, they can change shape and volume. The gas atoms being in a molecular state moves fast in high speed to break away from each other, to remain in a free state.
The two strands are held together by hydrogen bonds between the bases, with adenine forming a base pair with thymine, and cytosine forming a base pair with guanine.