Which best describes a compound such as sodium chloride?

a pure substance that can be separated into different elements by physical means
a mixture of two common substances that can be separated by chemical means
a mixture of two common elements that can be separated by physical means
a pure substance that can be separated into different elements by chemical means

Which part of earth’s surface receives the most direct rays from the sun? a) equator b) ocean c) poles d) mountains

Which statement about hf is true? it is zero for any compound in its standard state. it is positive when the bonds of the product store more energy than those of the reactants. it is negative when a compound forms from elements in their standard states. it is zero for any element that is in the liquid state.

3.09 lab: reaction of metals 1 which combinations of substances resulted in a chemical change? for each metal that participated in a chemical change, write the type of metal it is, based on your examination of the periodic table. were there any metallic compounds that did not react with either the acid or the base? write the type of metal, based on your examination of the periodic table. make a general statement about the reactivity of the metals in this experiment.