Answer : The crown is not made of pure (100%) gold.
Explanation :
Formula used :
where,
= apparent weight of the crown in water = 4.50 N
= actual weight = 5.00 N
= density of water = 
= density of crown = ?
Now put all the given values in the above formula, we get:
Density of crown < Density of gold
Thus, the crown is not made of pure (100%) gold.
Well actully the thunder is heard before the lightning because light travles faster than sound
The answer is ( The concentrations of the products and reactants do not change.)
The total mass of the products is 10.76 g + 204.44 g = 215.20 g.
The masses of all the reactants but one are known so,
215.20 g - 120.00 g - 8.15 g - 75.00 g = 12.05 g
12.05 g is the mass of the unweighed barium nitrate.
<h3>Further explanation</h3>
Given
Atomic symbol
Required
Atomic composition
Solution
Atomic number = number of protons = number of electrons
Mass Number (A) is the sum of protons and neutrons
Number of protons and Number of Neutrons in nucleus
Number of electrons in the shell
From the picture:
protons = 3
neutrons = 4
electrons = 3
atomic number = protons = electrons = 3
mass number = protons + neutrons = 3+4 = 7
