Answer:
Retrograde Motion
Explanation:
Geocentric model of planets was proposed by Ptolemy. It stated that all sun, planets and stars revolve round the earth in circular orbits.
NOTE: Ptolemy: an ancient astronomer, geographer, and mathematician who considered the Earth the center of the universe (the "Ptolemaic system").
I think the correct answer is the first option. It has nonpolar bonds and a symmetrical structure. The structure of a BF3 molecule shows a symmetrical trigonal geometry. The net dipole moment of the molecule is zero therefore it is polar.
<u>Answer:</u> The lewis dot structure is attached below.
<u>Explanation:</u>
A Lewis dot structure is defined as the representation of atoms having electrons around the atom where electrons are represented as dots.
A ketene is an organic compound having general formula R′R″C=C=O, where R and R' are two different/same monovalent chemical groups.
The given chemical compound having formula
is represented as
.
Total number of unshared electrons = 4 (left on oxygen atom only)
The lewis dot structure of
is given in the image below.
Answer:
Moles of Hydrogen produced is 5 moles
Explanation:
The balanced Chemical equation for reaction between zinc and sulfuric acid is :

This equation tells that ; when 1 mole of Zn react with 1 mole of sulfuric acid, it produces 1 mole of zinc sulfate and 1 mole of hydrogen.
Since sulfuric acid is in excess so Zinc is the limiting reagent
(Limiting reagent : Substance which get consumed when the reaction completes, limiting reagent helps in predicting the amount of products formed)
Limiting reagent (Zn) will decide the amount of Hydrogen produced


So,

Hence moles of Hydrogen produced is 5 moles
The decreasing order of wavelengths of the photons emitted or absorbed by the H atom is : b → c → a → d
Rydberg's formula :
,
where λ is the wavelength of the photon emitted or absorbed from an H atom electron transition from
to
and
= 109677 is the Rydberg Constant. Here
and
represents the transitions.
(a)
=2 to
= infinity
= 109677/4 [since 1/infinity = 0] Therefore,
= 4 / 109677 = 0.00003647 m
(b)
=4 to
= 20
= 6580.62
Therefore,
= 1 / 6580.62 = 0.000152 m
(c)
=3 to
= 10
= 11089.56
Therefore,
= 1 / 11089.56 = 0.00009 m
(d)
=2 to
= 1
= - 82257.75
Therefore,
= 1 /82257.75 = - 0.0000121 m
[Even though there is a negative sign, the magnitude is only considered because the sign denotes that energy is emitted.]
So the decreasing order of wavelength of the photon absorbed or emitted is b → c → a → d.
Learn more about the Rydberg's formula athttps://brainly.com/question/14649374
#SPJ4