An atom's mass number indicates a
the number of protons in the nucleus of an atom.
b
the number of neutrons in the nucleus of an atom.
c
the sum of the neutrons and electrons in the nucleus of an atom.
d
the sum of the neutrons and protons in the nucleus of an atom.
e
the charge of that atom's ion.

Classify this reaction: 2al+n2-> aln.

The atomic number, or number, is the described as the number of in the nucleus of an chemical element.

Two metal blocks that have slightly different temperatures are placed next to one another. after five minutes, they both have lower but equal temperatures. according to the law of conservation of energy, what  most likelyhappened? energy was created inside the blocks.energy was destroyed inside the blocks.energy was absorbed into the blocks from outside the system.energy was transferred from the warmer block to the cooler block.