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2 years ago

6

Mrs. Lu wanted to test which brand of dishwasher detergent cleaned her plates the best Theaning which one left the least amount

of
residue from spaghetti). She tested Cascade, Palmolive, and a generic brand. What is the independent variable?

1 answer:

Marina86 [1]2 years ago

3 0

Answer:

The independant variable is dishwasher detergant.

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Oxygen is a __________ and nitrogen is a __________. metalloid, metalloid nonmetal, metal nonmetal, nonmetal nonmetal, metalloid

Anna35 [415]

Answer:

"nonmetal, nonmetal"

Explanation:

Oxygen is a non metal and Nitrogen is a non metal. It is 8th element of the periodic table. It is located in period 2 and group 16.

Nitrogen lies at the group 15 of the periodic table. Its atomic no is 7. Its valency is 2.

Hence, the correct option is (c) "nonmetal, nonmetal".

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2 years ago

Cacl2 is an example of

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An ionic bond because ca is a metal and cl is a nonmetal which is an ionic bond

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2 years ago

Calculate the pH of the following simple solutions:

IceJOKER [234]

Answer :

(1) pH = 1.27

(2) pH = 13.35

(3) The given solution is not a buffer.

Explanation :

<u>(1) 53.1 mM HCl</u>

Concentration of HCl = $53.1mM=53.1\times 10^{-3}M$

As HCl is a strong acid. So, it dissociates completely to give hydrogen ion and chloride ion.

So, Concentration of hydrogen ion= $53.1\times 10^{-3}M$

pH : It is defined as the negative logarithm of hydrogen ion concentration.

$pH=-\log [H^+]$

$pH=-\log (53.1\times 10^{-3})$

$pH=1.27$

<u>(2) 0.223 M KOH</u>

Concentration of KOH = 0.223 M

As KOH is a strong base. So, it dissociates completely to give hydroxide ion and potassium ion.

So, Concentration of hydroxide ion= 0.223 M

Now we have to calculate the pOH.

$pOH=-\log [OH^-]$

$pOH=-\log (0.223)$

$pOH=0.65$

Now we have to calculate the pH.

$pH+pOH=14\\\\pH=14-pOH\\\\pH=14-0.65=13.35$

<u>(3) 53.1 mM HCl + 0.223 M KOH</u>

Buffer : It is defined as a solution that maintain the pH of the solution by adding the small amount of acid or a base.

It is not a buffer because HCl is a strong acid and KOH is a strong base. Both dissociates completely.

As we know that the pH of strong acid and strong base solution is always 7.

So, the given solution is not a buffer.

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2 years ago

Describe the temperature changes that occur in ice as energy is added, starting in the frozen state and ending in the vapor stat

Ket [755]

Explanation:

When water is frozen then it is known as ice and its state is solid. So, its molecules will be held closer to each other as they are held by strong intermolecular forces of attraction.

As a result, its temperature will be minimum as its molecules have least kinetic energy.

It is known that kinetic energy of a substance is directly proportional to temperature.

As, K.E = $\frac{3}{2}kT$

where K.E = kinetic energy

T = temperature

k = boltzmann constant

When solid changes into liquid state then it means molecules of a substance has gained kinetic energy due to which there occurs more collisions between the molecules.

Hence, temperature of substance also increases.

Whereas when liquid state of a substance changes intro vapor state then it means that more kinetic energy has gained by the molecules due to which there will be much more collisions between the molecules.

Hence, temperature will be maximum in vapor state.

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BJECTIVE TYPE QUESTIONS

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Answer:

1.Physical change

2. Chemical change

3. Heat

4.photosynthesis

5. composition

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