It took 380,000 years for electrons to be trapped in orbits around nuclei, forming the first atoms.
These were mainly helium and hydrogen, which are still by far the most abundant elements in the universe. Present observations suggest that the first stars formed from clouds of gas around 150–200 million years after the Big Bang. Heavier atoms such as carbon, oxygen and iron, have since been continuously produced in the hearts of stars and catapulted throughout the universe in spectacular stellar explosions called supernovae.
Answer:
a)hydroxide or you can say hydroxil ion OH-
P=m/V
m=40.24 g
V=50.0 mL=50.0 cm³
p=40.24/50.0=0.8048 g/cm³
<h2><u>Full Question:</u></h2>
The image shows a molecular model of a compound using balls and sticks. Each ball is an atom and each stick is a bond. If you were to use balls and sticks to model a molecule of an element, how must your model differ from what’s shown?
A. The sticks must be shorter.
B. The balls must be the same color.
C. The balls must be smaller.
D. The balls must change to cubes.
<h2><u>Answer:</u></h2>
The balls must be of same colour.
Option B.
<h3><u>Explanation:</u></h3>
A Molecule is defined as the smallest part of an element or compound which can exist freely in nature. An element is define as the matter which is when divided into smallest particles gives only one type of particle or atom. Where as a compound is defined as the combination of different elements in a particular ratio which has properties totally different from the combining elements. So an element comprises of only one type of atoms.
In this picture we can see that there is a central atom which is marked in blue where as the other atoms are peripheral and marked in red. The bonds between the blue atom and red atoms are marked with sticks. So if only one type of atoms are present in the molecule then only one coloured balls will be seen. Then the the colour of the balls will be only one.
Answer:
D a substance that increases the rate of a reaction without being used up itself in a reaction.
Explanation:
Examples are
ammonia synthesis ==> iron
sulfuric acid manufacture ==> nitrogen(II) oxide, platinum
cracking of petroleum==> zeolites
hydrogenation of unsaturated hydrocarbons ==> nickel, platinum, or palladium
I hope it helps