Which statements describe the principles of the big bang theory? check all that apply. the universe is continuing to expand. a massive explosion caused matter and energy to expand and form the universe. the cause of the big bang was dark matter and dark energy. the universe expanded, but its size is now remaining constant. the universe is slowly collapsing and getting smaller.

The big bang theory explains how the universe began. According to it, the universe began as singularity (a very hot , small and dense superforce with no stars, atoms, or structures) and then about 13.7 billion years ago, the space  expanded very quickly. This leads to formation of stars and galaxies which we know today. This expanding of universe is still happening and thus the temperature of universe is decreasing.

Therefore, the statements describing the bing bang theory are:

1) The universe is continuing to expand and

2)A massive explosion caused matter and energy to expand and form the universe.

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

if it's not useful, feel free to report for mistake in answer.

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)