Its basically a chart with all the known elements on it. The elements are organized by period and group. Period and group are determined by the number of protons and electrons an atome has.
Answer:
The mass of gold in crown is 960.61 g.And the volume of gold is
.
Explanation:
Density is defined as mass of the substance present in unit volume of the substance.
Mass of gold in an alloy of crown= m
Mass of silver in an alloy of crown = M
Volume gold in an alloy of crown= v
Volume of silver in an alloy of crown = V
Density of gold = 
Density of silver = 
Volume of the crown = 

..(1)
Mass of eh crown = 1050 g
..(2)
Solving equation (1) and (2):
m = 960.61 g
M = 89.39 g
Volume of the gold = v = 
Volume of silver = V = 
The mass of gold in crown is 960.61 g.And the volume of gold is
.
Answer:
B.) The molecule is a branched hydrocarbon.
Explanation:
A hydrocarbon is any molecule made up of carbon and hydrogen exclusively. A methyl- prefix denotes the presence of a methyl group (CH₃), which is situated as a branch off of a hydrocarbon carbon.
Well that is because the stratosphere has lower temperatures and low air density. This gives the airplane less air pressure and with low air density they can fly faster :) Hope this helps.