Answer:
c) i) Mg²⁺ ii) O²⁻
Explanation:
I don't know the answer to Q7. because you don't show the diagram
The first rule is to use four digits in atomic weights and consider the calculated formula or molar mass as given with four significant digits. This rule is appropriate for beginners but has some disadvantages.
The second rule is to use all digits in the recommended atomic weights and to estimate the accuracy of the result from the number of decimal places or significant digits in these.
The third rule is to use all digits in the recommended atomic weights and to calculate the absolute maximum uncertainty of the result from the recommended uncertainties of the atomic weights. The uncertainty is rounded up to one (two) significant digit(s), and the formula or molar mass is rounded to the same absolute accuracy as the rounded uncertainty.
Answer:
3.61 * 10 ²⁴atoms.
Explanation:
Moles is denoted by given mass divided by the molecular mass ,
Hence ,
n = w / m
n = moles ,
w = given mass ,
m = molecular mass .
From the question ,
w = 582 g
m = 194 g/mol
The number of moles can be calculated from the above formula , and substituting the respective values ,
n = w / m = 582 g / 194 g/mol = 3 mol
In the molecular formula of caffeine ,
<u>In 1 mole of caffeine their are - 2 moles of Oxygen.
</u>
Therefore , in 3 moles of Caffeine there will be 6 moles of oxygen.
As well know ,
one mole of any substance contains 6.023*10²³ atoms,
Therefore , in 6 mol of oxygen = 6 * 6.023*10²³ atoms = 3.61 * 10 ²⁴atoms.
That is called one centimeter
