Answer:

Explanation:
Given that,
Frequency of a radio antenna is 1 MHz
Power, P = 21 kW
We need to find the the waves intensity 25 km from the antenna
. The object emits intenisty evenly in all direction. It can be given by :

So, the wave intensity 25 km from the antenna is
.
Answer:
k = 104.46 N/m
Explanation:
Here we can use energy conservation
so we will have
initial gravitational potential energy = final total spring potential energy
as we know that she falls a total distance of 31 m
while the unstretched length of the string is 12 m
so the extension in the string is given as


so we have



Answer:
c
Explanation:
c. the ability to do work or to produce heat
My calculator is about 1cm thick, 7cm wide, and 13cm long.
Its volume is (length) (width) (thick) = (13 x 7 x 1) = 91 cm³ .
The question wants me to assume that the density of my calculator
is about the same as the density of water. That doesn't seem right
to me. I could check it easily. All I have to do is put my calculator
into water, watch to see if sinks or floats, and how enthusiastically.
I won't do that. I'll accept the assumption.
If its density is actually 1 g/cm³, then its mass is about 91 grams.
The choices of answers confused me at first, until I realized that
the choices are actually 1g, 10² g, 10⁴ g, and 10⁶ g.
My result of 91 grams is about 100 grams ... about 10² grams.
Your results could be different.
OF2 -
<span>O has 6 electrons in outer shell and F has 7 in its outer shell </span>
<span>Therefore, you have to account for 20 electrons total in the </span>
<span>structure (7+7+6 = 20) </span>
<span>therefore draw it linear first. F ---- O-----F </span>
<span>The two bonds take care of 4 electrons now you have to add another 16. </span>
<span>Therefore 3 lone pairs on each F and 2 lone pair on O. </span>
<span>If you check for formal charges, all the atoms are neutral </span>
<span>F will have 3 lone pairs + 1 bond = 7 electrons (bond = 1/2 electron for formal charge distribution) therefore both the F's are neutral </span>
<span>Now look at the O: it should have 6.. it has two lone pair and 2 bonds = 4 electrons and 2 bonds = 1 electron each = 2 electrons from bonds = 6 total electrons for formal charge which is exactly the # it should have. There is no need for any double bond in this as there are no charges to be separated. </span>
<span>Now if u look at the # of domains around O you will see if you include the lone pairs it has a sp3 hybridization (4 domains) therefore a tetrahedron which has 2 lone pairs and 2 bonds.. since there are two lone pairs, the lone pair/bond pair repulsion is so high it is going to repel the two Fluorines and form a bent structure, looks a lot like H2O. </span>