Steam is often used as a central heating system when heating many buildings froma central location. So the correct option for the given question is option "D". Steam is actually generated ina single room or place mechanically or by useing fossil fuel or solar energy and then it is passed through pipelines to several rooms and buidings. This kind of system is mostly used when heating several rooms or building at once. Electric heaters are normally avoided as the cost of electricity is far higher than any other source of heating.
Answer:
Temperature at the bottom will be 19.18°C
Explanation:
We have given height h = 807 m
Temperature at the top 
Specific heat of water c = 4200 
From energy conservation
Kinetic energy at the bottom = potential energy at the top
So 
So temperature at the bottom = 17.3+1.88 = 19.18°C
An atom is defined as having the same number of electrons (negative charge), protons (positive charge) and neutrons (no charge). This means that it will have the same amount of negative and positive charge, giving it a net zero charge. On the other hand, an ion has different amount of electrons and protons.
Lungs is what helps u breath
