The charges for four ions are sodium (Na) +1, calcium (Ca) +2, fluorine (F) –1, and sulfur (S) –2. Which would be an ionic bond
that could form from any of these ions?
A.NaCa2
B.Na2S
C.CaF
D.FS
A.NaCa2
B.Na2S
C.CaF
D.FS
2 answers:
Answer: B.
Explanation: An ionic bond is formed when an element completely transfers its valence electron to another element. Ionic bond is formed between a metal and an non-metal.
For formation of a neutral ionic compound, the charges on cation and anion must be balanced. The cation is formed by loss of electrons by metals and anions are formed by gain of electrons by non metals.
Here is having an oxidation state of +1 and sulfur has an oxidation state of -2. Thus they combine to form neutral
.
is having an oxidation state of +2 and fluorine has an oxidation state of -1. Thus they combine to form neutral
. and not
.
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a) Average power: 1425 W
b) Instantaneous power at 3.0 sec: 2850 W
Explanation:
a)
The motion of the object along the ramp is a uniformly accelerated motion (because the force applied is constant), so we can use the suvat equation
where
s = 18 m is the displacement along the ramp
u = 0 is the initial velocity
t = 3.0 s is the time taken
a is the acceleration of the object along the ramp
Solving for a,
Now we can apply Newton's second law to find the net force on the object:
This net force is the resultant of the applied force forward () and the component of the weight acting backward (
), so we can find what is the applied force:
where
m = 24 kg is the mass of the object
is the acceleration of gravity
Now we can finally find what is the work done by the applied force, which is parallel to the ramp, therefore:
where s = 18 m is the displacement.
Therefore the average power needed is:
b)
The instantaneous power at any point of the motion is given by
where
is the force applied
v is the velocity of the object
We already calculated the applied force:
While since this is a uniformly accelerated motion, we can find the velocity at the end of the 3.0 seconds using the suvat equation:
And therefore, the instantaeous power at 3.0 sec is:
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Answer: See attachment below
Explanation:
We can solve the problem by using Snell's law, which states
where
is the refractive index of the first medium
is the angle of incidence
is the refractive index of the second medium
is the angle of refraction
In our problem,
(refractive index of air), 
and 
(refractive index of carbon disulfide), therefore we can re-arrange the previous equation to calculate the angle of refraction:
From which we find
where
In our problem,
From which we find