Answer:
78.3 × 10²³ atoms of helium are present in 52 g.
Explanation:
Given data:
Mass of He = 52 g
Number of atoms = ?
Solution:
First of all we will calculate the number of moles of He
Number of moles = mass /molar mass
Number of moles = 52 g/ 4 g/mol
Number of moles = 13 mol
The given problem will solve by using Avogadro number.
It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.
The number 6.022 × 10²³ is called Avogadro number.
For example,
1 mole = 6.022 × 10²³ atoms of helium
13 mol × 6.022 × 10²³ atoms of helium / 1 mole
78.3 × 10²³ atoms of helium
Answer:
A). An atom is an indivisible hard-sphere.
Explanation:
The 'Atomic Theory' of Dalton is characterized as the earliest model(came in 1803) which described the atoms as the indivisible and resistant spheres. He <u>used the example of watermelon to elaborate that the atoms of a specific element share similar characteristics</u> and the atoms of distinct elements differ in their mass as well as their size. Thus, <u>option A</u> is the correct answer.
Answer:
The element is Rubidium . The ion only loss one electron to make the electron 36 . But the proton number(atomic number) is 37. The chemical compound should RbBr
X = Rubidium(Rb)
Explanation:
The ion of element X has a mass number of 85 and electron of 36. An elements is charge if it either loss or receive electron. Base on the charge the ion has loss electron. Bromine usually possess a negatively charge ion. That makes the X electron a positively charge ion.
proton number = Atomic number
Proton number = electron number when not charged
Mass number = proton number + neutron number
Proton is usually same number with the electron to make the element neutral. But when the atom is charge the atom usually loss or gain electron.
In this case, the atom X loss one electron thereby reducing the electron number to 36 . Recall, the electron is equal to proton only if the atom is uncharged. This means the proton number should be 37 as one electron was loss.
Element with proton number(atomic number) of 37 is rubidium. It is an alkali metal that is very reactive.
Answer:
He would travel 3 kilometers.
Explanation:
Since he had already covered 1.5 kilometers in the time of 1 hour that means if he jogged for 1 more hour assuming he is going at the same pace he would've jogged 1.5 kilometers again and when you add that to the 1.5 kilometers he started with it would add up to 3 kilometers.