The fully balanced equation would be
4Fe + 3O2 --> 2Fe2O3
for each side, we have
4 Fe (4 iron)
6 Oxygen (O)
So the final answer is choice B) 3
Given :
Mass of granite , m = 20 g .
Change in temperature , 
.
Specific heat capacity of granite , 
.
To Find :
The heat absorbed by granite .
Solution :
We know , heat absorb is given by :
Therefore , heat absorb is 300.2 J .
Hence , this is the required solution .
Mass of a substance = Moles of a substance × molar mass of a substance
We have 0.94 moles of NaHCO3. The molar mass of NaHCO3 is the sum of the atomic masses of the elements comprising NaHCO3, which is approximately 84.007 g/mol.
The mass of 0.94 moles of sodium bicarbonate is therefore (0.94 moles NaHCO3)(84.007 g NaHCO3/mol NaHCO3) = 78.97 ≈ 79 grams of sodium bicarbonate.
Answer:
Option B = atomic number
Explanation:
Electrically neutral atom:
An electrically neutral atom have equal number of protons and neutrons. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other. For example if neutral atom has 6 protons than it must have 6 electrons. The number of protons or number of electrons are the atomic number of an atom while the number of protons and number of neutrons are the mass number of an atom. Every atom consist of nucleus or a positive center. The protons and neutrons are present with in the nucleus while electrons are present out side the nucleus. All these three subatomic particles construct an atom.
Example:
Consider the example of carbon. It consist of six protons and six electrons. So, its atomic number is six. While the six neutrons are also present in nucleus with six protons that’s why its mas number is 12.
Electron:
The electron is subatomic particle that revolve around outside the nucleus and has negligible mass. It has a negative charge.
Symbol= e⁻
Mass= 9.10938356×10⁻³¹ Kg
It was discovered by j. j. Thomson in 1897 during the study of cathode ray properties.
Neutron and proton:
While neutron and proton are present inside the nucleus. Proton has positive charge while neutron is electrically neutral. Proton is discovered by Rutherford while neutron is discovered by James Chadwick in 1932.
Symbol of proton= P⁺
Symbol of neutron= n⁰
Mass of proton=1.672623×10⁻²⁷Kg
Mass of neutron=1.674929×10⁻²⁷ Kg
Answer: two moles
Explanation:
In one mole of fe2o3 there are two moles of iron atoms. Now gram atomic wt. of Fe is 56.So in one mole of Fe2O3 there are 2×56=112 gm of Fe. Hence in 1.75molesFe2O3 there are 1.75×2 moles or 1.75×56 gm of iron
