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3 years ago

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Chemistry

1 answer:

Vika [28.1K]3 years ago

7 0

Answer:

Option B is correct.

Explanation:

An atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.

All these three subatomic particles construct an atom. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other. The number of protons or neutrons is the atomic number of an atom while sum of proton and neutrons is the mass number.

The beryllium atom have five neutrons, four protons and four electrons.

The option be is correct model of beryllium because it shows that there are four protons and five neutron in nucleus of beryllium atom and four electrons revolving around the nucleus.

Beryllium is alkaline earth metal.

It is present in group two.

Its atomic number is 4.

its atomic mass is 9 amu.

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If 200. mL of 0.60 M MgCl2(aq) is added to 400 mL of distilled water, what is the concentration of Mg and Cl in the resulting so

sladkih [1.3K]

Answer:

C. 0.20 M Mg ion & 0.40 M Cl ion

Explanation:

MgCl₂ is a ionic salt which is dissociated as this

MgCl₂ → Mg²⁺ + 2Cl⁻

First of all, we have a solution of 200 mL, with [MgCl₂] = 0.6M

Molarity . volume = moles.

0.6 mol/l . 0.2l = 0.12 mol

MgCl₂ → Mg²⁺ + 2Cl⁻

0.12mol 0.12 0.24

This moles are also in 400mL of water, so the new concentration is

[Mg²⁺] = 0.12 m/0.6L = 0.2M

[Cl⁻] = 0.24 m/0.6L = 0.4M

Remember we initially have 200mL and then, we add 400 mL, so we supose aditive volume. (600mL)

8 0

3 years ago

If you have a pitcher of lemonade and the recipe calls for 2 lemons and you decided to use 4, would this be considered diluted o

pantera1 [17]

Answer: This would be considered concentrated because if you're upping the recipe on your own accord, it would be way more sour, causing the lemonade to be more concentrated. It would be diluted if you added less than 2 lemons.

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3 years ago

Noble Gases (18): (Name all noble gases)

Paul [167]

Answer :

The Noble gasses are Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn).

When air is cold, Oxygen liquefies first at $-182^oC$ . $N_2$ liquefies at $-195^oC$ . About 1% of the air is still gas composed of the noble gas Argon, Ar.
One noble gas was discovered on the sun. It’s spectrum was identify first. This is Helium, He.
One of noble gas is radioactive and seeps up your basement floors and walls. It is Radon, Rn.
This noble gas is used in electronic flashes and other bright lights. It is Xenon, Xe.
This noble gas is best known for its orange color in gas discharge tubes. It is used for signs that bear its name. It is Neon, Ne.

3 0

3 years ago

Fluoride is moderately basic, by far the most basic of the halides. It is a terrible leaving group. Fluoride is many orders of m

TEA [102]

Answer: Bromide is many orders of magnitude better than fluoride in leaving group ability

Explanation:

As Size of an atom Increases, the Basicity Decreases this is because if we move downwards from the top of the periodic table to the bottom of the periodic table, the size of an atom increases. As size increases, basicity will decrease, meaning the element will be less likely to act as a base implying that the element will be less likely to share its electrons.

in the same vein. With an increase in size, basicity decreases, making the ability of the leaving group to leave increase to increase . This can be seen in the halogens going down the group from

F--- worst

Cl----fair

Br ----good

I-----excellent

with fluorine having the worst ability to leave than Bromine which is better in terms of the leaving group ability.

3 0

3 years ago

A chemist prepares a solution of potassium dichromate by measuring out of potassium dichromate into a volumetric flask and filli

riadik2000 [5.3K]

Answer:

0.297 mol/L

Explanation:

<em>A chemist prepares a solution of potassium dichromate by measuring out 13.1 g of potassium dichromate into a 150 mL volumetric flask and filling the flask to the mark with water. Calculate the concentration in mol/L of the chemist's potassium dichromate solution. Be sure your answer has the correct number of significant digits.</em>

<em />

Step 1: Calculate the moles corresponding to 13.1 g of potassium dichromate

The molar mass of potassium dichromate is 294.19 g/mol.

13.1 g × (1 mol/294.19 g) = 0.0445 mol

Step 2: Convert the volume of solution to L

We will use the relationship 1 L = 1000 mL.

150 mL × (1 L/1000 mL) = 0.150 L

Step 3: Calculate the concentration of the solution in mol/L

C = 0.0445 mol/0.150 L = 0.297 mol/L

4 0

3 years ago