Q: Which of the following is a central role of carbon in the chemistry of living organisms?
A: Carbon can form many types of molecules with covalent bonds.

Q: What is a galaxy?
A: a very large system of stars that is held together by gravity

Q: A recycling plant manager needs to melt 1500 kg of scrap copper to sell to a wire manufacturer. The copper is at 15C and its melting point is 1083C. The copper has a specific heat of 385 J/kg x K. How much heat is required to raise the temperature of the copper to its melting point?
A: 6.2 x 10^8 J

Q: Sulfur (S), oxygen (O2), water (H2O), and sodium chloride (NaCl) are all examples of pure substances. Which of the following describes all pure substances?
A:
A pure substance has a definite chemical composition.