Seen from the north pole, which side of a waxing moon is illuminated

How quickly can bacterial contamination occur?

NeX [460]

5-10 seconds xxx :) hope this helps

5 0

2 years ago

Read 2 more answers

Which of these was not proposed by john dalton in 1805?

wel

Answer:

Atoms are made of protons, neutrons and electrons.

Explanation:

The Dalton's atomic theory was an early attempt at describing the properties of atoms. It stipulated that atoms were the smallest indivisible particle of a substance. Chemical reactions occur as a result of a combination or separation of atoms. Atoms of the same element are exactly alike and differ from atoms of other elements. Atoms can neither be created nor destroyed.

As time went on, modern scientific evidence began to modify the original postulates of the Dalton's atomic theory. It was not postulated in 1805 that atoms were composed of subatomic particles; electrons, neutrons and protons. Dalton's theory held the atom to be 'indivisible'. However in 1897, JJ Thompson discovered the electron. Subsequently, the proton and neutrons were discovered. This shows that the atom in itself consisted of even smaller particles.

3 0

1 year ago

Which balanced redox reaction is occurring in the voltaic cell represented by the notation of A l ( s ) | A l 3 ( a q ) | | P b

frez [133]

The question is missing. Here is the complete question.

Which balanced redox reaction is ocurring in the voltaic cell represented by the notation of $Al_{(s)}|Al^{3+}_{(aq)}||Pb^{2+}_{(aq)}|Pb_{(s)}$ ?

(a) $Al_{(s)}+Pb^{2+}_{(aq)} ->Al^{3+}_{(aq)}+Pb_{(s)}$

(b) $2Al^{3+}_{(aq)}+3Pb_{(s)} -> 2Al_{(s)}+3Pb^{2+}_{(aq)}$

(c) $Al^{3+}_{(aq)}+Pb_{(s)} ->Al_{(s)}+Pb^{2+}_{(aq)}$

(d) $2Al_{(s)}+3Pb^{2+}_{(aq)} -> 2Al^{3+}_{(aq)}+3Pb_{(s)}$

Answer: (d) $2Al_{(s)}+3Pb^{2+}_{(aq)} -> 2Al^{3+}_{(aq)}+3Pb_{(s)}$

Explanation: Redox Reaction is an oxidation-reduction reaction that happens in the reagents. In this type of reaction, reagent changes its oxidation state: when it loses an electron, oxidation state increases, so it is oxidized; when receives an electron, oxidation state decreases, then it is reduced.

Redox reactions can be represented in shorthand form called cell notation, formed by: left side of the salt bridge (||), which is always the anode, i.e., its half-equation is as an oxidation and right side, which is always the cathode, i.e., its half-equation is always a reduction.

For the cell notation: $Al_{(s)}|Al^{3+}_{(aq)}||Pb^{2+}_{(aq)}|Pb_{(s)}$

Aluminum's half-equation is oxidation:

$Al_{(s)} -> Al^{3+}_{(aq)}+3e^{-}$

For Lead, half-equation is reduction:

$Pb^{2+}_{(aq)}+2e^{-} -> Pb_{(s)}$

Multiply first half-equation for 2 and second half-equation by 3:

$2Al_{(s)} -> 2Al^{3+}_{(aq)}+6e^{-}$

$3Pb^{2+}_{(aq)}+6e^{-} -> 3Pb_{(s)}$

Adding them:

$2Al_{(s)}+3Pb^{2+}_{(aq)} -> 2Al^{3+}_{(aq)}+3Pb_{(s)}$

The balanced redox reaction with cell notation $Al_{(s)}|Al^{3+}_{(aq)}||Pb^{2+}_{(aq)}|Pb_{(s)}$ is

$2Al_{(s)}+3Pb^{2+}_{(aq)} -> 2Al^{3+}_{(aq)}+3Pb_{(s)}$

6 0

2 years ago

Magnesium metal burns with a bright white flame. What conclusions can you draw about the electron transitions that can take plac

Verizon [17]

Different wavelength are involved.

Explanation:

If magnesium burns with a bright white flame, one can conclude that different wavelengths accompany the electron transitions for the magnesium atom.

When an atom burns, the electrons in it are excited.
They give out characteristic light commensurate with their energy.
A white light is made up of different combinations of wavelength of radiations.
When we see a white light we can infer that different joined together in the emission observed.

Learn more:

Spectrum brainly.com/question/6255073

#learnwithBrainly

3 0

1 year ago

2 attempts left select the single best answer. The radii of the lithium and magnesium ions are 76 pm and 72 pm, respectively. Wh

Lina20 [59]

The ionic character of any compound depend on the lattice energy as well as the electronegativity of element present in that compound.

More would be the lattice energy more would be ionic nature of that compound.

The lattice energy of any compound is inversely proportional to the ionic radii cation and anion.

In given case the ionic radii of oxide in both oxides would be equal therefore the lattice energy only depend on the ionic radii of cation.

$Lattice energy (U) = \frac{1}{Ionic radii}$

As the radii of Magnesium less then radii of lithium therefore lattice energy of Magnesium oxide would be more than lithium oxide.

Hence, MgO would be more ionic in nature than $Li_{2}O$

8 0

1 year ago