Answer:
0.4m/s²
Explanation:
Given parameters:
Mass of student = 50kg
Force = 20N
Unknown:
Acceleration = ?
Solution:
From Newton's second law of motion,
Force = mass x acceleration
Acceleration = 
= 
= 0.4m/s²
Answer:
The energy absorbed in the first move is greater than the energy released in the second move.
Explanation:
The greater the level number the greater the energy.
A movement up a level requires energy so energy id absorbed.
Dropping down a level releases energy.
Answer: There was a lower concentration of salt in the water than in the cells.
Explanation:
Osmosis is a process in which the solvent flow from a solution of low concentration to a solution of high concentration through a semi-permeable membrane.
When the red blood cells are put in water that contained salt and the red blood cells burst after some time.
This means the solvent has moved from outside to inside the cell and this is possible only when the concentration of solute is high inside the cell than outside. That means the solution has low concentration of solute as compared to the cell and was a hypotonic solution.
Answer :
The number of bonding pairs of electrons around the hydrogen atom = 2
The number of lone pairs of electrons around the hydrogen atom = 0
Explanation :
Lewis-dot structure : It shows the bonding between the atoms of a molecule and it also shows the unpaired electrons present in the molecule.
In the Lewis-dot structure the valance electrons are shown by 'dot'.
The given molecule is, 
As we know that carbon has '4' valence electrons, hydrogen has '1' valence electrons and nitrogen has '5' valence electrons.
Therefore, the total number of valence electrons in = 1 + 4 + 5 = 10
According to Lewis-dot structure we conclude that, there are 8 number of bonding electrons and 2 number of non-bonding electrons.
The number of bonding pairs of electrons around the hydrogen atom = 2
The number of lone pairs of electrons around the hydrogen atom = 0
The statement that best explains why magnesium and chlorine combine in a 1:2 ratio is; Magnesium has two valence electrons, and chlorine can accept one electron in its outer shell.
The number of electrons that an atom of an element has in its outermost shell determines the chemical formula of the compounds formed by atoms such elements.
Magnesium is in group 2, as such it has two electrons in its outermost shell while chlorine in group 17 only accepts one electron in its outermost shell. This one electron will give chlorine an inert gas configuration while the loss of two electrons give magnesium an inert gas configuration.
Therefore; The compound MgCl2 is formed in the ratio of 1:2 because Magnesium has two valence electrons, and chlorine can accept one electron in its outer shell.
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