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4vir4ik [10]
3 years ago
8

Why is helium considered as a noble gas

Chemistry
2 answers:
dolphi86 [110]3 years ago
7 0
Noble gases are known for having a full outer shell of electrons which helium has as it has two electrons its first electron shell is completely filled

larisa [96]3 years ago
3 0
Helium is  considered a noble gas because it has 8 valence electrons, as well as it also is a stable element. Meaning that it consists of a full octet. 
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A liquid has a density of 1g/mL. If you have 50mL of the liquid, what would its mass be?
Svetlanka [38]

Answer:

<h2>The answer is 50 g</h2>

Explanation:

The mass of a substance when given the density and volume can be found by using the formula

<h3>mass = Density × volume</h3>

From the question

volume of liquid = 50 mL

density = 1g/mL

The mass of the liquid is

mass = 50 × 1

We have the final answer as

50 g

Hope this helps you

8 0
3 years ago
What is the answer pllleeaasseeeee?????
kenny6666 [7]

I will try my best to sovle this question...

Im Pretty sure it has to be A. it needs to balance it would not stand in place if not balanced.

3 0
3 years ago
5.2 G of HCl are dissolved in 25 mL of solution. What is the molarity?
Kobotan [32]

Answer:

0.21 M

Explanation:

Molarity is the calculation of the solution in which the number of solute per liter of the solutions. It is the most common measurement unit that is used to measure the concentration of the solution.

The molarity is the unit that is used to measure or calculate the volume of the solvent. The amount of solvent is used in the chemical reaction.

The amount of the two solvent in the same quantity is measured by the formula called c1v1 and c2v2.

6 0
3 years ago
Given 4.80g of ammonium carbonate, find:
V125BC [204]

Answer:

1) 0.05 mol.

2) 0.1 mol.

3) 0.05 mol.

4) 0.4 mol.

5) 2.4 x 10²³ molecules.

Explanation:

<em>1) Number of moles of the compound:</em>

no. of moles of ammonium carbonate = mass/molar mass = (4.80 g)/(96.09 g/mol) = 0.05 mol.

<em>2) Number of moles of ammonium ions :</em>

  • Ammonium carbonate is dissociated according to the balanced equation:

<em>(NH₄)₂CO₃ → 2NH₄⁺ + CO₃²⁻.</em>

It is clear that every 1.0 mole of (NH₄)₂CO₃ is dissociated to produce 2.0 moles of NH₄⁺ ions and 1.0 mole of CO₃²⁻ ions.

<em>∴ The no. of moles of NH₄⁺ ions in 0.05 mol of (NH₄)₂CO₃ </em>= (2.0)(0.05 mol) =  <em>0.1 mol.</em>

<em>3) Number of moles of carbonate ions :</em>

  • Ammonium carbonate is dissociated according to the balanced equation:

<em>(NH₄)₂CO₃ → 2NH₄⁺ + CO₃²⁻.</em>

It is clear that every 1.0 mole of (NH₄)₂CO₃ is dissociated to produce 2.0 moles of NH₄⁺ ions and 1.0 mole of CO₃²⁻ ions.

∴ The no. of moles of CO₃²⁻ ions in 0.05 mol of (NH₄)₂CO₃ = (1.0)(0.05 mol) = 0.05 mol.

<em>4) Number of moles of hydrogen atoms:</em>

  • Every 1.0 mol of (NH₄)₂CO₃  contains:

2.0 moles of N atoms, 8.0 moles of H atoms, 1.0 mole of C atoms, and 3.0 moles of O atoms.

<em>∴ The no. of moles of H atoms in 0.05 mol of (NH₄)₂CO</em>₃ = (8.0)(0.05 mol) = <em>0.4 mol.</em>

<em>5) Number of hydrogen atoms:</em>

  • It is known that every mole of a molecule or element contains Avogadro's number (6.022 x 10²³) of molecules or atoms.

<u><em>Using cross multiplication:</em></u>

1.0 mole of H atoms contains → 6.022 x 10²³ atoms.

0.4 mole of H atoms contains → ??? atoms.

<em>∴ The no. of atoms in  0.4 mol of H atoms</em> = (6.022 x 10²³ molecules)(0.4 mole)/(1.0 mole) = <em>2.4 x 10²³ molecules.</em>

8 0
3 years ago
Which of these describes an endothermic process?
Phoenix [80]
The third one down: "When barium hydroxide is mixed with ammonium chloride, ice crystals form on the outside of the container."

This is because an endothermic reaction [process] takes in more energy than it releases. Therefore because a decrease in energy leads to a decrease in temperature, the ice crystals forming show that it must be a endothermic reaction [process].

Hope this helps! :)
AJ
3 0
3 years ago
Read 2 more answers
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