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valina [46]
3 years ago
11

Which of these is an element?

Chemistry
2 answers:
Yanka [14]3 years ago
6 0

Answer:

A.

Explanation:

The rest are molecules and/or compounds

just olya [345]3 years ago
3 0
B
Sksnksnsksksksksksksks
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By means of a schematic diagram show how a bacteria cell applied to the region of a cowpea root can end up becoming a nitrate io
GenaCL600 [577]

Answer:

Nitrifying Bacteria are a group of aerobic bacteria important in the nitrogen cycle as converters of soil ammonia to nitrates, compounds usable by plants. An example is nitrosomonas or nitrobacter and species in that family.

The schematic diagram is attached below, which summarises the oxidation of ammonia or free nitrogen in the soil to nitrates for the cowpea plant's utilisation.

4 0
3 years ago
An atom (not a hydrogen atom) absorbs a photon whose associated wavelength is 300 nm and then immediately emits photon whose ass
KIM [24]

Answer:

The net energy is 2.196 eV

Explanation:

Basically, the energy of an atom increases when it absorbs a photon. In addition, the wavelength of the emitted photon is longer such that the atom absorbed a net energy in the process.

Using:

ΔE = h*c*(1/λ_{1} - 1/λ_{2})

where:

ΔE is the net energy in eV (electron-volt). 1 eV is equivalent to 1.602*10^{-19} J.

h = 4.135*10^{-15} eVs

c = 3*10^{8} m/s

λ_{1} = 300 nm = 300*10^{-9} m

λ_{2} = 640 nm = 640*10^{-9} m

Thus:

ΔE = 4.135*10^{-15} eVs*3*10^{8} m/s*(\frac{1}{300*10^{-9}m } }-\frac{1}{640*10^{-9}m })

ΔE = 4.135*10^{-15}*3*10^{8}*1.77*10^{6} eV = 2.196 eV

6 0
3 years ago
If you filter a mixture of sand and salt-water, what will the solid residue in the filter paper consist of?
julia-pushkina [17]
Sand only bc the salt dissolved and sand doesn't
8 0
3 years ago
.........................................................................
AVprozaik [17]
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3 years ago
A galvanic cell at a temperature of 25.0°C is powered by the following redox reaction:
soldi70 [24.7K]

Answer:

2.01V ( To three significant digits)

Explanation:

First we show the standard reduction potentials of Cu2+(aq)/Cu(s) system and Al3+(aq)/Al(s) system. We can clearly see from the balanced redox reaction equation that aluminium is the anode and was the oxidized specie while copper is the cathode and was the reduced specie. This observation is necessary when substituting values of concentration into the Nernst equation.

The next thing to do is to obtain the standard cell potential as shown in the image attached and subsequently substitute values of concentration and standard cell potential into the Nernst equation as shown. This gives the cell potential under the given conditions.

5 0
3 years ago
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