Answer:
b) 2.0 mol
Explanation:
Given data:
Number of moles of Ca needed = ?
Number of moles of water present = 4.0 mol
Solution:
Chemical equation:
Ca + 2H₂O → Ca(OH)₂ + H₂
now we will compare the moles of Ca and H₂O .
H₂O : Ca
2 : 1
4.0 : 1/2×4.0 = 2.0 mol
Thus, 2 moles of Ca are needed.
Answer:
Neutrons = 11
Explanation:
To get the number of neurons an element has you have to subtract the number of protons from the atomic mass of that element.
The number of protons is equal to the atomic number of that element.
Atomic number = Number of Protons
So the number of protons is 25
Neutrons = Atomic mass - Number of Protons
Neutrons = 36 - 25
Neutrons = 11
An orbital that penetrates into the region occupied by core electrons is less shielded from nuclear charge than an orbital that does not penetrate and therefore has a lower energy.
Explanation:
The only true statement from the given options is that "an orbital that penetrates into the region occupied by core electrons is less shielded from nuclear charge than an orbital that does not penetrate and therefore has a lower energy." Inner orbitals which are also known to contain core electrons feels the bulk of the nuclear pull on them compared to the outermost orbitals containing the valence electrons.
- The nuclear pull is the effect of the nucleus pulling and attracting the electrons in orbitals.
- This pull is stronger for inner orbitals and weak on the outer ones.
- The outer orbitals are said to be well shielded from the pull of the nuclear charge.
- Also, based on the quantum theory, electrons in the outer orbitals have higher energies because they occupy orbitals at having higher energy value.
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Answer:
The new pressure is 3850 torr.
Explanation:
The relation between volume and pressure is inverse as per Boyle's law. Its mathematical form is given by :
Here,
Let 
is the new pressure. So using Boyle's law we get :
or
So, the new pressure is 3850 torr.
