Answer:
Explanation:
Temperature of air = 18°C = 273 + 18 = 291 K .
volume = 500 cc = 0 .5 litre .
pressure = one atmosphere ( atm) .
From gas equation , we can calculate this volume at NTP as follows.
volume = .5 x ( 273 / 291 ) litre
= 0.469 litre .
In any gas at NTP , 22.4 litre contains 6.02 x 10²³ molecules
.469 litre will contain 6.02 x 10²³ x .469 / 22.4 molecules
= 126 x 10²⁰ molecules .
b )
one mole = 6.02 x 10²³ molecules
6.02 x 10²³ molecules has weight of 28.96 grams
126 x 10²⁰ molecules has weight of 28.96 x 126 x 10²⁰ / 6.02 x 10²³ grams
= .606 gram .
c )
volume of all the air in the atmosphere = volume of sphere
= 4 / 3 x π x R³
= ( 4 / 3) x 3.14 x (999.5 x 10³ )³ m³
= 4.18 x 10¹⁸ m³
density of air = 1.225 kg / m³
mass of air = 1.225 x 4.18 x 10¹⁸ kg
= 5.12 x 10¹⁸ kg
d )
volume of air inhaled by 7 billion people
= . 5 x 7 x 10⁹ litre
= 3.5 x 10⁶ m³ .
Total volume of air in atmosphere = 4.18 x 10¹⁸ m³
required percentage
= 3.5 x 10⁶ x 100 / 4.18 x 10¹⁸
= .8373 x 10⁻¹⁰ % .
Answer:
HERE IS YOUR ANSWER
Explanation:
1. The machines makes pur life easier.
2. It makes us do our works faster.
3. It does all the works that are harder for us.
Hope it helps you.
Answer: All apply
The periodic table is an arrangement of the chemical elements in the form of a table, ordered by:
-Their atomic number (number of protons)
-Their configuration of electrons
-Their chemical properties
It was progressively developed over time as the scientific knowledge advanced; for this reason many modifications and corrections might be done in the future.
Its usefulness lies in the fact that it allows the existing elements to be organized in a more structured and coherent way, according to the chemical properties they possess. Dividing the table into rows and columns, which represent the periods and groups or families.
Then, with the location and classification of an element according to its group, we can determine how it acts by knowing its chemical and physical characteristics.
This is how with this configuration can be distinguished 4 sets of chemical elements, according to the ease of their atoms to lose or gain electrons, transforming into ions: metals, semimetals, non-metals and noble gases.
This has helped to predict the existence of various elements that have not yet been discovered, because by elements already located in the table and the periodicity found, <u>there are still empty spaces that indicate the composition of the element that has not yet been found</u>.
In addition, this table helps to simplify in some way the teaching of chemical elements and facilitates their learning, as well as their usage in the development of technological innovations.
