Answer:

Explanation:
The water droplet is initially neutral, it will obtain a 40 nC of charge when a charge of -40 nC is removed from the water droplet.
The charge on one electron, 
Let the N number of electrons have charge -40 nC, such that,
Now, mass of one electron = 
Therefore, mass of N electrons = 
It is the mass of the of the water droplet that must be removed in order to obtain a charge of 40 nC.
Let it is m times the total mass of the droplet which is 
Then,

It is the required fraction of mass of the droplet.
From the law of the lever:
<span>mechanical advantage= input arm : output arm
input arm- a
output arm-b
</span>

<span>Input arm is equal 4,8m</span>
The fastest speed before the string breaks is 9.5 m/s
Explanation:
The motion of the block is a uniform circular motion, which is a circular motion with constant speed. The force that keeps the block in circular motion is called centripetal force; its direction is towards the centre of the circle and its magnitude is given by:

where
m is the mass of the block
v is its speed
r is the radius of the circle
In this problem, the centripetal force is provided by the tension in the string, T, so we can write:

The string breaks when the centripetal force becomes larger than the maximum tension in the string:

Re-arranging the equation for v,

and here we have:
T = 450 N
m = 10 kg
r = 2 m
Substituting,

So, the fastest speed before the string breaks is 9.5 m/s.
Learn more about circular motion:
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Nitrogen could form 3 bonds based on octet rule, because it has 5 valence electrons. That means it needs 3 bonds.
Explanation:
- A nitrogen atom can fill its octet by sharing three electrons with another nitrogen atom, forming three covalent bonds, a so-called triple bond.
- A triple bond isn't quite three times as strong as a single bond, but it's a very strong bond.
- Every covalent bond is a sharing of two electrons between two atoms. A double bond is 4 electrons being shared (2x2). Therefore a triple bond is 6 electrons being shared (2x3)
- Triple bonds are stronger than double bonds due to the the presence of two pi bonds rather than one.
- Each carbon has two sp hybrid orbitals, and one of them overlaps with its corresponding one from the other carbon atom to form an sp-sp sigma bond.
- A single lone pair can be found with atoms in the nitrogen such as nitrogen in ammonia , two lone pairs can be found with atoms in the chalogen group such as oxygen in water and the halogen can carry three lone pairs such as in hydrogen chloride. Nitrogen has 2 lone pairs.