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3 years ago

Why was 1990 an important year regarding air quality?

Chemistry

1 answer:

Rus_ich [418]3 years ago

7 0

Answer:

The United States took first steps to keep the air clean.

Explanation:

The US environmental protection agency was created in the year 1970 so this option is wrong.

November 15, 1990 however was a milestone in keeping the air clean, the signing f the amendments, the amendments set the stage for protecting the ozone layer, improving air quality and visibility.

The correct option is option A; The United States took first steps to keep the air clean.

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A sample of seawater consists of water, sodium ions, chloride ions, and several other dissolved salts. These ions and salts are

stellarik [79]

Answer:

Mixture, homogeneous mixture, solution

Explanation:

A mixture is defined as a substance which is made by physical combination of two or more substance.

As in sea water, more than two substance are present, therefore is considered as mixture.

A mixture is considered as homogeneous mixture, if it has same proportion of components through out the mixture. In sea water proportions of all the components are same, therefore, its is also a homogeneous mixture.

In solution, solute is dissolved in a solvent and the concentration of the solute is same through out the solution.. In sea water, sodium ions, chloride ions, and several other salts are dissolved in water. Therefore, water is considered as solvents and components present are considered as solute.

so, sea water can also considered as solution.

Among the given options, 1, 3 and 4 are correct

So, sea water is considered as mixture, homogeneous mixture and solution.

6 0

2 years ago

A helium balloon is filled on the ground where the atmospheric pressure is 768 torr. The volume of the balloon is 8.00 m3. When

Anvisha [2.4K]

Answer:

The correct option is: B. 366 torr

Explanation:

Given: On the ground- Initial Volume: V₁ = 8.00 m³, Initial Atmospheric Pressure: P₁= 768 torr;

At 4200 m height- Final Volume: V₂ = 16.80 m³, Final Atmospheric Pressure: P₂ = ?

Amount of gas: n, and Temperature: T = constant

According to the Boyle's Law, for a given amount of gas at constant temperature: P₁ V₁ = P₂ V₂

⇒ P₂ = P₁ V₁ ÷ V₂

⇒ P₂ = [(768 torr) × (8.00 m³)] ÷ (16.80 m³)

⇒ P₂ = 365.71 torr ≈ 366 torr

Therefore, the final air pressure at 4200 m height: P₂ = 366 torr.

6 0

3 years ago

A 3.0-mol sample of kclo3 was decomposed according to the equation 2kclo3(s) --> 2kcl(s) + 3o2(g) how many moles of o2 are fo

d1i1m1o1n [39]

2moles of O2 are formed.

5 0

2 years ago

Which substance can not be broken down by a

Tomtit [17]

Answer: (3) silicon

Explanation:

Element is a pure substance which is composed of atoms of similar elements.It can not be decomposed into simpler constituents using chemical reactions.Example: Silicon (Si)

Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: ethane $(C_2H_6)$ , propanone $(CH_3COCH_3)$ and water $(H_2O)$

7 0

2 years ago

1.65g of zinc is used to make 8g of zinc iodide. How much iodine is required for this reaction?

creativ13 [48]

Answer:

6.45 g of iodine, I₂

Explanation:

We'll begin by writing the balanced equation for the reaction. This is illustrated below:

Zn + I₂ —> ZnI₂

Next, we shall determine the mass of Zn and I₂ that reacted from the balanced equation. This can be obtained as follow:

Molar mass of Zn = 65 g/mol

Mass of Zn from the balanced equation = 1 × 65 = 65 g

Molar mass of I₂ = 127 × 2 = 254 g/mol

Mass of I₂ from the balanced equation = 1 × 254 = 254 g

SUMMARY:

From the balanced equation above,

65 g of Zn reacted with 254g of I₂.

Finally, we shall determine the mass of f I₂ needed to react with 1.65 g of Zn. This can be obtained as follow:

From the balanced equation above,

65 g of Zn reacted with 254g of I₂.

Therefore, 1.65 g of Zn will react with = (1.65 × 254)/65 = 6.45 g of I₂.

Thus, 6.45 g of iodine, I₂ is needed for the reaction.

4 0

3 years ago