Explanation:
The given data is as follows.
, 
Work produced per kJ of heat extracted from hot reservoir = 0.45 kJ = Efficiency
If the device is Carnot cycle then its efficiency will be maximum and its value will be equal to ![[1 - (\frac{T_{c}}{T_{h}} )]](https://tex.z-dn.net/?f=%5B1%20-%20%28%5Cfrac%7BT_%7Bc%7D%7D%7BT_%7Bh%7D%7D%20%29%5D)
Using this relation we will calculate the efficiency as follows.
Efficiency = ![[1 - (\frac{T_{c}}{T_{h}} )]](https://tex.z-dn.net/?f=%5B1%20-%20%28%5Cfrac%7BT_%7Bc%7D%7D%7BT_%7Bh%7D%7D%20%29%5D)
=
= 0.928
Hence, it means that this type of device is possible and the claim is also believable.
1.51 x 10²⁵atoms
Explanation:
Given parameters:
Mass of Na = 578g
Unknown:
Number of atoms = ?
Solution:
To find the number of atoms, we must first find the number of moles the given mass contains.
Number of moles = 
molar mass of Na = 23g
Number of moles =
= 25.13moles
1 mole of a substance = 6.02 x 10²³atoms
25.13 mole of Na = 25.13 x 6.02 x 10²³atoms
This gives 1.51 x 10²⁵atoms of Na
Learn more:
Avogadro's constant brainly.com/question/2746374
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Answer: B. 1:2
Explanation: Beryllium and chlorine forms a binary ionic compound. Ionic compound is formed when a metal loses its electrons to a receiving non metal. Beryllium (metal) has two valence electrons while chlorine (nonmetal) has seven valence electrons, and so a beryllium atom has to give out its two valence electrons to attain a duplet stable structure while a chlorine atom will gain one electron to attain its stable octet structure. In the reaction between beryllium and chlorine, two atoms of chlorine have to accept the two electrons from one beryllium atom to attain their stable octet structure.
The formula of the compound formed is BeCl2.