There are very clear differences between past and present life including the following:
The technological side ; Life in ancient times lacked the tools of technology that man knew in modern times, so people's lives were difficult and difficult in many ways. In traveling, people traveled from country to country using camels, and at home people used simple primitive tools to set fire to the food. . In today's world, people are competing in the use of technology in all aspects of their private and public life. In people's homes you find most tools that make it easier for people to live and get away from hardship and fatigue, shorten time, effort and money. From one place to another thousands of miles away in a few hours.
"Pure substances are defined assubstances that are made of only one type of atom or molecule"