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3 years ago

How have safety concerns about chemicals changed over time?

Chemistry

1 answer:

Alex787 [66]3 years ago

8 0

Answer:

C. As scientists have learned more about chemicals, they have become more aware of their dangers

Explanation:

Chemicals are substances with standard compositions, held together by chemical bonds. Chemicals can exist in different phases such as solid, liquid, and gaseous phases. Over time, with a growing understanding of chemicals, their composition, and their reaction methods, scientists now have a better knowledge of the dangers chemicals can pose. To that effect, they have created standard safety measures for those who have to work with these chemicals.

When these guidelines are strictly adhered to, the chances of suffering accidents, burns, and explosions with these chemicals are significantly reduced.

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A neutral atom in the ground state has four electrons in its fifth and outermost principal energy level. What element is it?

Zepler [3.9K]

Answer:

Tin

Explanation:

Tin is an element which belongs to the carbon family in the periodic table. It lies in group 14 of the periodic table i.e. IV a.

The symbol of Tin is Sn. Tin has 50 electron in total. Its atomic number is 50. The 50 electrons of tin are divided in its five energy shells. The outer most or the valence shell contains 4 electrons in the ground state.

The number of electrons present per shell in tin is : 2, 8, 18, 18, 4.

The electronic configuration of tin is : [Kr] 4d¹⁰5s²5p²

7 0

3 years ago

Why is it that the shoreline tends to have milder temperatures in the winter than mainland?

Volgvan

I think its becuse the shoreline is shalow water that is warmed by the sun? ...... I may be rong

7 0

3 years ago

A solution of HCl gas dissolved in water (sold commercially as "muriatic acid," a solution used to clean masonry surfaces) has 2

disa [49]

Answer:

[HCl] = 6.09 M

Xm HCl = 0.11

Explanation:

Let's analyse data:

20.22 g of solute / 100 g of solution

Solution's density = 1.10 g/mL

As we have the mass of solution and its density we determine solution's volume to stablish [M]

Density = Mass / volume → 1.10 g/mL = 100 g / Volume

100 g / 1.10g/mL = 90.9 mL

Let's convert the volume to L → 90.9 mL . 1L/ 1000mL = 0.0909L

We convert the mass of solute to moles → 20.22 g . 1mol/ 36.45g =

0.554 moles

[M] = Molarity (moles of solute /1L of solution) = 0.554 mol/0.0909L = 6.09M

Mole fraction (Xm) = Moles of solute / Total moles

Total moles = Moles of solute + Moles of solvent

Mass of solvent = Mass of solution - Mass of solute

Mass of solvent = 100 g - 20.22 g = 79.78g

We convert the mass to moles → 79.78 g / 18g/mol = 4.43 moles

Total moles = 4.43 moles + 0.554moles = 4.984 moles

Xm = 0.554 / 4.984 = 0.11

6 0

3 years ago

Provide three ways that humans have had a impact on the greenhouse effect on Earth?

galina1969 [7]

Burning of fossil fuels, increase use of vehicles and use of household appliances like refrigerator are the three ways humans have had an impact on the greenhouse effect on Earth

<u> Explanation:</u>

Burning of fossil fuels for industrial purpose cause the emission of greenhouse gases such as Chlorofluorocarbons (CFCs), Carbon dioxide, methane and nitrous oxide.

The smoke comes from the vehicles contain carbon dioxide which increases the number of greenhouse gases in the atmosphere .

Use of household appliances will also lead to the emission of greenhouses gases mainly, CFCs (Chlorofluorocarbons) .

Increase in the number of greenhouse gases in the atmosphere will lead to climate change.

8 0

4 years ago

A large scuba tank with a volume of 18 L is rated for a pressure of 220 bar. The tank is filled at 20 °C and contains enough air

Marina CMI [18]

Answer:

Yes, at 20 °C the tank was filled to full capacity

Explanation:

Given;

let initial pressure, P₁ = 2.37 atm

let initial volume, V₁ = 1860 L

let final pressure, P₂ = 220 bar = 217.123 atm

let final volume, V₂ = ?

Subject the air volume (1860 L ) at 2.37 atm to the tank rating (220 bar)

Ideal law is given by;

PV = nRT

At a fixed mole and gas temperature, the equation becomes;

P₁V₁ = P₂V₂

V₂ = (P₁V₁) / P₂

V₂ = (2.37 x 1860) / 217.123

V₂ = 20.3 L

After subjecting the air volume to tank rating, the volume of the air at 220 bar is 20.3 L which is greater than tank volume (18 L).

The extra 2.3 L can be assumed to be compressed gas volume due to the given (lower) temperature.

Thus, at 20 °C the tank was filled to full capacity.

3 0

4 years ago