2. which is the correct element for the atom with 42 protons and 49 neutrons?

Indium

Explanation:

Elements are pure substances that can not be broken down into smaller particles using chemical means.They are made up of atoms that contains sub-atomic particles protons, neutrons and electrons.The number of protons and electrons in a neutral atom of an element are equal.Neutrons and protons are found in the nucleus of an atom.Different elements have different number of protons and neutrons.An element with an atom that has 42 protons and 49 neutrons in its nucleus is Indium.

Matter- occupies space and possesses rest massno matter is the opposite

They can measure  the amount of energy gained or lost