<span>Answer:
Some metals have the ability to form differently charged ions. For example, iron can form
2
+
or
3
+
ions. If you simply gave the name iron chloride, you would not know which charge the iron ion possessed.
A Roman numeral is to indicate the charge of the iron.
Iron (
II
) means the iron has a
2
+
charge
Iron (
III
) means that the iron has a
3
+
charge
So, iron (
II
) oxide would have a chemical formula of
FeO
.
(The oxide ion has a
2
â’
charge to balance the
2
+
of the iron to form a neutral compound.)
Iron (
III
) oxide would have a chemical formula of
Fe
2
O
3
(Here you need to find the common multiple of 6, so two iron ions with a
3
+
charge will balance the charge of three oxide ions with a
2
+
charge.)</span>
Answer and Explanation:
The Fremy salt is a chemical compound its chemical name is disodium nitrosodisuphonate
The molecular formula of the Fremy salt is 
When phenol is treated with Fremy salt in presence of water then benzoquinone is formed
( in presence of Fremy salt and water)
The atomic number tells us the number of protons and electrons.
The atomic mass tells us the weight of the nucleus, which is the amount of protons and neutrons
FALSE You are never allowed to stand on the top of the ladder even if all legs are on the ground
Answer: 
Explanation:
Engineering notation : It is the representation of expressing the numbers that are too big or too small and are represented in the decimal form times 10 raise to the power. It is similar to the scientific notation but in engineering notation, the powers of ten are always multiples of 3.
The engineering notation written in the form:
where,
a = the number which is greater than 0 and less than 999
b = an integer multiple of 3
Now converting the given value of 2,469,100 into engineering notation, we get
Hence, the correct answer is,
