PLEASE HELP URGENT 1. at how much energy is required to melt a 30.0-gram sample of water at its melting point?

2. at 1 atmosphere of pressure, 20.0 g of a compound at its normal boiling point are converted to a gas by the addition of 23,000 joules. what is the heat of vaporization for the compound in J/g?

Identify one disadvantage to each of the following models of electron configuration: -dot structures -arrow and line diagrams -written electron configurations type in your answer below. (answer) -dot structures do not show the distribution of electrons in orbitals and take up a lot of space. -arrow and line diagrams take up a lot of space and make it difficult to count electrons. -written configurations make it easy to lose count of electrons and do not show the distribution of electrons in orbitals.

May someone me with these science questions

Which of the following are sources of revenue for media companies? a. direct sales to producers b.advertising and subscriptions c. online purchase d. capital investments