An element is a pure substance that has not been combined with anything, whereas a compound is something that is made of two or more substances (elements). an element would be Gold, and Silver, and a compound would be table salt or water.
An organ system is contained inside an organism. Going from largest to smallest it goes organism->organ system-> organ-> tissue-> cell-> atom
Answer:
129.453 kJ is required to heat 0.850 pints of water
Explanation:
1 pint requires 36400 cal of energy to heat a pint of water from room temperature to boil.
Sometimes he uses 0.850 pints. The energy he needs then : 36400 * 0.85 = 30940 cal
Since we know that 1 cal = 4.184 J
⇒ 1 cal = 4.184J so 30940 cal =4.184 * 30940 = 129452.96 J = 129.453 kJ
So 0.850 pints of water require 129.453 kJ, at roomtemperature.
In an atom, the nucleus is composed of positive charged particles called protons and neutrons that have zero charge. Most of the mass of the atom is in the nucleus. The atom is surrounded by orbits of electrons that are mobile and are negatively charged.