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4 years ago

Why was 1990 an important year regarding air quality?

Chemistry

1 answer:

Rus_ich [418]4 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 student titrates a 20.00 mL sample of an aqueous borax solution with 1.03 M H2SO4. If 2.07 mL of acid are needed to reach the

RSB [31]

Answer:

The concentration of the borax solution is 0.1066 M

Explanation:

Step 1: Dtaa given

Volume of a sample of aqueous borax solution = 20.00 mL = 0.020 L

Molarity of H2SO4 = 1.03 M

Volume of the H2SO4 = 2.07 mL = 0.00207 L

Step 2: The balanced equation

Na2B4O7*10H2O(borax) + H2SO4 ⇆ Na2SO4 + 4 H3BO3 + 5 H2O

Step 3: Calculate molarity of borax solution

b*Ca*Va = a * Cb*Vb

⇒with B = the coefficient of H2SO4 = 1

⇒with Ca = the concentration of borax = TO BE DETERMINED

⇒with Va = the volume of borax = 0.020 L

⇒with a = the coefficient of borax = 1

⇒with Cb = the concentration of H2SO4 = 1.03 M

⇒with Vb = the volume of H2SO4 = 0.00207 L

Ca*0.020 L = 1.03 M * 0.00207 L

Ca = (1.03 * 0.00207) / 0.020

Ca = 0.1066 M

The concentration of the borax solution is 0.1066 M

6 0

4 years ago

The table shows the recipe and the available ingredients for making the maximum possible number of sandwiches.

Serhud [2]

Answer:

B. 4 ham slices

Explanation:

A chemical reaction involves one or more substances known as reactants combining chemically to give one or more substances known as products.

Reactants in chemical reactions combine in definite mole or mass ratios to give products. Therefore, when one substance is present in excess of what is required to combine with another to form products, that substance is known as the excess reagent. The other substance which is present in a smaller amount and which when used up, the reaction stops is known as the limiting reagent.

From the illustration of the sandwiches in the question, the recipe for one sandwich represents the chemical equation of a reaction. The equation form is given below:

2 cheese slices + 1 ham slice + 2 bread slices ---> 1 sandwich

The ratio of the reactant is 2 : 1 : 2

From the available ingredients, 12 cheese slices, 10 ham slices, 12 bread slices.

12 cheese slices will require 6 ham slices and 12 bread slices to produce 6 sandwiches.

However, since there are 10 ham slices, 4 ham slices will be left over unused. This is the excess or leftover reactant.

8 0

3 years ago

Matter is the substance that we can see and observe. True False

SSSSS [86.1K]

I'd say true.
Matter is a physical substance that occupies space.
Lets say you put random stuff in a box. That stuff is matter, filling the box.
Its common to say that matter is everything around you. You can see everything around you (almost).

3 0

4 years ago

The amino acid methionine can be used as fuel by being converted to succinyl CoA. What would be the estimated ATP yield for the

andre [41]

Answer:

18 molecules of ATP will be produced for the breakdown of methionine to succinyl CoA and the entry of succinyl CoA to the citric acid cycle with no input of glucose.

Explanation:

Reactions reduced co enzymes ATP formation

α keto glutarate to propionyl CoA 2 NADH 6 moles

Succinyl CoA to succinate 2 GTP≈ 2 ATP

Succinate to fumarate 2FADH2 4 moles

Malate to oxaloacetate 2 NADH 6 moles

3 0

3 years ago

20 According to the kinetic molecular theory for an ideal gas, all gas particles(1) are in random, constant, straight-line motio

AnnyKZ [126]

According to the kinetic molecular theory for an ideal gas, all gas particles "have collisions that decrease the total energy of the system" but this is not always the case.

5 0

3 years ago