A scientific model is a simplified version of some phenomenon that takes place in natural systems. A scientific model can be visual (flow charts), graphical, conceptual, or mathematical. These models are used to make predictions about how a set of conditions would change the present scenario in future. Scientific models can explain how the ongoing changes in the environment can show long term affect on our planet like the climate change. Therefore, a scientific model can be used to explain the phenomena like the effect of global air temperatures on the mean sea level around the world.
<u>Answer:</u> The balanced chemical equation is written below.
<u>Explanation:</u>
Galvanization is defined as the process in which a protective layer of zinc is applied to iron or steel to prevent the metal from rusting.
Zinc prevents the oxidation of iron and acts as a reducing agent in the process.
The half reaction for the process follows:
<u>Oxidation half reaction:</u> 
<u>Reduction half reaction:</u> 
Net chemical equation: 
Hence, the balanced chemical equation is written above.
We assume that we have Ka= 4.2x10^-13 (missing in the question)
and when we have this equation:
H2PO4 (-) → H+ + HPO4-
and form the Ka equation we can get [H+]:
Ka= [H+] [HPO4-] / [H2PO4] and we have Ka= 4.2x10^-13 & [H2PO4-] = 0.55m
by substitution:
4.2x10^-13 = (z)(z)/ 0.55
z^2 = 2.31x 10^-13
z= 4.81x10^-7
∴[H+] = 4.81x10^-7
when PH equation is:
PH= -㏒[H+]
= -㏒(4.81x10^-7) = 6.32
Answer:
Increasing atomic number - True
Explanation:
The modern table is based on Mendeleev’s table, except the modern table arranges the elements by increasing atomic number instead of atomic mass.
The Atomic number is the number of protons in an atom, and this number is unique for each element. For example, Hydrogen has an atomic number of 1, Calcium has an atomic number of 20.
In the modern periodic table the elements are further arranged into:
- rows, called periods, in order of increasing atomic number. Elements in the same periods have the same number of shells.
- vertical columns, called groups, where the elements have similar properties. Elements in the same group has the same number of valency (outermost number of electrons)
1) Calcium carbonate contains 40.0% calcium by weight.
M(CaCO₃)=100.1 g/mol
M(Ca)=40.1 g/mol
w(Ca)=40.1/100.1=0.400 (40.0%)!
2) Mass fraction of this is excessive data.
3) The solution is:
m(Ca)=1.2 g
m(CaCO₃)=M(CaCO₃)*m(Ca)/M(Ca)
m(CaCO₃)=100.1g/mol*1.2g/40.1g/mol=3.0 g
