The most abundant in the atmosphere are Nitrogen, Oxygen, Argon, and Carbon Dioxide. All of these combined take up about 99.9% of the Earths atmosphere
True All somatic cells have same genes but the genes whose product is not needed are turned off. Some genes are expressed constitutively and some genes are turned off and on depending upon the requirement of proteins.
Ice formation is a phase change from liquid to solid. The ice is less dense so its volume gets larger. Warm it up, melt the ice and it will return to the same volume it had as a liquid.
