Part (a):
Chalk has the chemical formula: CaCo₃
From the periodic table:
mass of Ca = 40 grams
mass of Co = 58.9 grams
Therefore:
molecular weight of chalk = 40 + 3(58.9) = 216.7 grams
Part (b):
Advantages of M<span>andeleev's periodic table:
1- Could predict the properties of elements easily based on its position in the periodic table
2- Elements were arranged systematically in order of increasing atomic mass which helped in the study and classification of elements
3- Even after the discovery of noble gases, no major changes needed to be done to the periodic table. Noble gases were inserted easily
4- He left room for other undiscovered elements based on his systematic approach in writing the table
Hope this helps :)</span>
Answer:
171.34 g/mol
Explanation:
Ba molar mass = 137.328 g/mol
O molar mass = 15.999 g/mol * 2 = 31.9980 g/mol
H molar mass = 1.008 g/mol * 2 = 2.0160 g/mol
137.328 + 31.9980 + 2.0160 = 171.3420 = 171.34 g/mol
Answer: The correct answer is (D).
Explanation:
Space photography help astronomers:
- To visualize and observe the position and appearance of celestial objects like: path of orbiting planets ,dim stars which invisible to naked eyes ,far away galaxies etc.
- To observe any phenomena which is occurring at macro level for example: collision of steroids and meteors etc.
Answer:
The correct answer is - A. Ethanol reduces air pollution.
Explanation:
Ethanol is believed to be better fuel for the environment than other petroleum fuels. Ethanol emits lower carbon dioxide as it is clean smokeless fuel, and produces less or the same oxides of nitrogen and hydrocarbons.
It is produced by the process of fermentation of molasses by yeast. Mixing it with the other fuels is found to be CO2 reduces by 30% of emissions to the atmosphere.
Largest to smallest: barium, calcium, selenium, oxygen
