7.(03.01 mc)
which of the following statements does not describe the structure of an atom? (3 point
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inside the nucleus of an atom are protons and neutrons.
protons are positively charged sub-atomic particles.
electrons are negatively charged sub-atomic particles.
most of the mass of an atom comes from the electron cloud.

Most of the mass of an atom comes from the electron cloud.

Explanation:

All options are correct except,

Most of the mass of an atom comes from the electron cloud. Because,

Most of mass comes from nucleus in which protons and neutrons are present.

The electron is subatomic particle that revolve around outside the nucleus and has negligible mass. It has a negative charge.

Symbol= e-

Mass= 9.10938356×10-31 Kg

It was discovered by j. j. Thomson in 1897 during the study of cathode ray properties

While neutron and proton are present inside the nucleus. Proton has positive charge while neutron is electrically neutral. Proton is discovered by Rutherford while neutron is discovered by James Chadwick in 1932.

Symbol of proton= P+  

Symbol of neutron= n0  

Mass of proton=1.672623×10-27 Kg

Mass of neutron=1.674929×10-27 Kg

An atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.