Answer:
All matter is made up of substances called elements, which have specific chemical and physical properties and can't be broken down into other substances through ordinary chemical reactions. Gold, in this case, is an element so, therefore, it is considered matter.
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8.9 g + 90 g = 98.9 Copper has a density
Answer:-
Alpha decay
Explanation:-
Uranium 238 has atomic number 92 and mass number 238.
Thorium 234 has atomic number 90 and mass number 234.
So, the change in atomic number as uranium 238 disintegrates into thorium234 = 92 – 90 = 2
So, the change in mass number as uranium 238 disintegrates into thorium234= 238 – 234 = 4
We know that when an alpha particle is emitted, the mass number decreases by 4 and the atomic number decreases by 2.
So when an atom of uranium 238 undergoes radioactive decay to form an atom of thorium-234, alpha decay has occurred.
Answer:
A strip of magnesium metal is ignited using a lighter wand. The result is
an intensely glowing white light. As the burning of the metal subsides, a
white powder-like substance now appears replacing the smooth ribbon of
metal.