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vlada-n [284]
3 years ago
15

: If k is Kendra’s present age, write an expression for her age eight years ago. A. k + 8 B. 8 - k C. 8 + k D. k - 8

Chemistry
1 answer:
ohaa [14]3 years ago
5 0

Answer:

D. k - 8

Explanation:

brainest plz

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What happens to the mass of substances during a physical change?
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Here are the answers in order:

1. During a physical change the substance changes physically.

2. The law of conservation of mass is a law stating the conservation of mass cannot be higher than 46mg or lower than 32mg.

3. A hypothesis is a guess that you make before completing a science experiment, it can be considered a law because it is important to know why you are making the guess.

4. During a chemical change the mass is changing colors. This is a representation of a chemical change.

5. Oil is a non-renewable resource, so it cannot demonstrate the conservation of mass.

6. When the color of the substance has changed or when it explodes.

7. Reactants are the objects that react when in a chemical change.

8. If you follow the rule of not going higher than 46mg and not lower than 32mg then it will automatically follow this law.

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Questions again:

1. A chemical reaction

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3. Because if it is no higher than 46mg and no lower than 32mg then it will follow on it's own.

8 0
3 years ago
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An ideal liquid mixture of benzene and toluene (50% by volume each) is used in a plant at 27°C and 1 atm. Determine (a) the mixt
cestrela7 [59]

Answer:

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Explanation:

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7 0
3 years ago
Which of the following statements correctly relates mutations and survival rates of plants?
Tasya [4]
Answer is: <span>Mutations sometimes improve the chances of survival for a plant.
</span>Mutations are very important because they change <span>variability in populations and in that way enable evolutionary change.
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3 0
3 years ago
A formic acid buffer solution contains 0. 20 m h c o o h hcooh and 0. 24 m h c o o − hcoox−. the pka of formic acid is 3. 75. wh
irina1246 [14]

A buffer solution contains an equivalent amount of acid and base. The pH of the solution with an acid dissociation constant (pKa) value of 3.75 is 3.82.

<h3>What is pH?</h3>

The amount of hydrogen or the proton ion in the solution is expressed by the pH. It is given by the sum of pKa and the log of the concentration of acid and bases.

Given,

Concentration of salt [HCOO⁻] = 0.24 M

Concentration of acid [HCOOH] = 0.20 M

The acid dissociation constant (pKa) = 3.75

pH is calculated from the Hendersons equation as,

pH = pKa + log [salt] ÷ [acid]

pH = 3.75 + log [0.24] ÷ [0.20]

= 3.75 + log (1.2)

= 3.75 + 0.079

= 3.82

Therefore, 3.82 is the pH of the buffer.

Learn more about pH here:

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6 0
2 years ago
Gizmo Warm-up
Mariana [72]

Sodium hydroxide solution and hydrogen gas are produced from the reaction of water and sodium.

<h2>Reaction of sodium and water</h2>

We observe bubbles coming out of the water when the sodium reacts with the water because of the formation of hydrogen gas which is insoluble in water so it moves into the atmosphere.

<h3>Products of the reaction</h3>

Sodium metal reacts rapidly with water to form sodium hydroxide (NaOH) solution and hydrogen gas (H2). This chemical reaction is exothermic because huge amount of heat is release from the solution so we can conclude that sodium hydroxide solution and hydrogen gas are produced from the reaction of water and sodium.

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8 0
2 years ago
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