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3 years ago

What is the mass of an element with 78 protons and 78 neutrons

Chemistry

2 answers:

stepan [7]3 years ago

8 0

Mass number=number of protons+number of neutrons
so mass number of the element you stated = 78+78 = 156 au

Reika [66]3 years ago

4 0

156. Atomic mass if the number of protons and neutrons within an atom.

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What is the frequency of electromagnetic radiation with a wavelength of 6.34 x 10^8 m?

Svetllana [295]

<h2>Answer: 4.72 × 10⁷ s⁻¹ or Hz</h2><h3> Explanation: </h3>

frequency = speed of light ÷ wavelength

frequency = (2.99 × 10⁸ m/s) ÷ (6.34 × 10⁸ m)

= 4.72 × 10⁷ s⁻¹ or Hz

8 0

3 years ago

Compare strontium with rubidium in terms of the following properties:

Ilya [14]

Answer:

Strontium is smaller

Strontium has the higher ionization energy

Strontium has more valence electrons

Explanation:

It must be understood that both elements belong to the same period i.e the same horizontal band of the periodic table

While Rubidium is an alkali metal(group 1) while Strontium is an alkali earth metal(group 2)

Since they are in the same period, periodic trends would be useful in evaluating their properties

In terms of atomic radius, rubidium is larger meaning it has a bigger atomic size

Generally, across the periodic table, atomic radius is expected to decrease and thus Rubidium which is leftmost is expected to have the higher atomic radius

Since strontium belongs to group 2 of the periodic table, it has 2 valence electrons which is more than the single valence electron that rubidium which is in group 1 has

In terms of ionization energy, the atom with the higher number of valence electrons will have the higher ionization energy which is strontium in this case

6 0

4 years ago

A chemical reaction occurring in a cylinder equipped with a moveable piston produces 0.601 mol of a gaseous product. If the cyli

netineya [11]

Answer:

4.33 L

Explanation:

Assuming ideal behaviour and that all 0.300 moles of gas reacted, we can solve this problem using Avogadro's law, which states that at constant temperature and pressure:

V₁n₂ = V₂n₁

Where in this case:

V₁ = 2.16 L

n₂ = 0.601 mol

V₂ = ?

n₁ = 0.300 mol

We <u>input the given data</u>:

2.16 L * 0.601 mol = V₂ * 0.300 mol

And <u>solve for V₂</u>:

V₂ = 4.33 L

3 0

3 years ago

Which reactions are oxidation-reduction reactions? check all that apply. fes(s) 2hcl(aq) â†’ h2s(g) fecl2(g) agno3(aq) nacl(aq)

Dafna1 [17]

oxidation-reduction reactions are -

2C3H6(g) + 9O2(g) → 6CO2(g) + 6H2O(g)
Fe2O3(s) + 3CO(g) → 2Fe(l) + 3CO2(g)

For reaction,

2C3H6(g) + 9O2(g) → 6CO2(g) + 6H2O(g)

<u>On reactant side</u>:

Oxidation state of Carbon = +2

Oxidation state of Oxygen = 0

<u>On product side:</u>

Oxidation state of Carbon = +4

Oxidation state of Oxygen = -2

Here, carbon's oxidation state is rising from +2 to +4. As a result, it is oxidizing and the oxygen's oxidation state is decreasing from 0 to -2. As a result, it is decreasing.

For reaction,

Fe2O3(s) + 3CO(g) → 2Fe(l) + 3CO2(g)

<u>When reacting:</u>

Iron's oxidation state is +3.

Carbon's oxidation state is +2.

<u>On product side:</u>

Iron's oxidation state is zero.

Carbon's oxidation state is +4.

Here, carbon's oxidation state is rising from +2 to +4. As a result, it is being oxidized and the iron's oxidation state is changing from +3 to 0. As a result, it is decreasing.

To learn more about oxidation-reduction from given link

brainly.com/question/5794822

#SPJ4

7 0

2 years ago

The muscles in the stomach aid in digestion by __________.

dsp73

Churning or mixing food.

The stomach is a muscular sac that lies between theesophagus and thesmall intestine in the upper abdomen. The stomach is not the only part of your digestive system that absorbs food but rather is a part of the digestive system and important for churning food into a consistency that is easier to digest for the rest of your intestines.

4 0

3 years ago

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