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natta225 [31]
3 years ago
11

Which change is the best example of a physical change?

Chemistry
2 answers:
goldenfox [79]3 years ago
7 0
A physical change does not change the bonds and it changes the state of the substance. 

A cookie baking is wrong because we cannot change it back to dough after it bakes. 

A paper burning is wrong also. Burning is a chemical change.

Ice cream melting can always be frozen back again, so that is correct!

A nail rushing is a chemical change, so it is wrong.

Final answer:- 3) ice cream melting


Ede4ka [16]3 years ago
3 0
A physical change would be 3) ice cream melting. 1) and 2) are combustion reactions, which are chemical with oxygen, and 4) is an oxidation reaction, also with oxygen. A phase change, or melting, is not a chemical change but a physical one. Therefore 3) ice cream melting is the answer
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What is the percentage by volume of hydrogen peroxide in typical first aid kits?
mrs_skeptik [129]
The answer to this question is that the percentage by volume of a hyrdrogen peroxide in mostly first aid kits contains 3%. Hydrogen peroxide or H2O2 is a compound that can be used as an antiseptic in orderto prevent infections from spreading in the bruises, cuts, and even burns. Hydrogen peroxide can also be used as a bleaching agent and an oxidizer.
4 0
4 years ago
The reaction of an arrhenius acid with an arrhenius base produces water and
aleksandr82 [10.1K]

Answer: salt

Explanation:

Arrhenius acids are substances which dissociate in water to give H^+ ions.

HCl\rightarrow H^++Cl^-

Arrhenius bases are substances which dissociate in water to give OH^- ions.

NaOH\rightarrow Na^++OH^-

Thus when they combine, they neutralize each other and produce salt and water.

HCl+NaOH\rightarrow NaCl+H_2O

6 0
3 years ago
A sample of food containing 27 g of fat, 48 g of carbohydrates and 20 g of protein is burned in a bomb calorimeter. In a perfect
rosijanka [135]

Answer:

38.3958 °C  

Explanation:

As,

1 gram of carbohydrates on burning gives 4 kilocalories  of energy

1 gram of protein on burning gives 4 kilocalories  of energy

1 gram of fat on burning gives 9 kilocalories of energy

Thus,

27 g of fat on burning gives 9*27 = 243 kilocalories of energy

20 g of protein on burning gives 4*20 = 80 kilocalories  of energy

48 gram of carbohydrates on burning gives 4*48 = 192 kilocalories  of energy

Total energy = 515 kilocalories

Using,

Q=m_{water}\times C_{water}\times (T_f-T_i)

Given: Volume of water = 23 L = 23×10⁻³ m³

Density=\frac{Mass}{Volume}  

Density of water= 1000 kg/m³

So, mass of the water:  

Mass\ of\ water=Density \times {Volume\ of\ water}  

Mass\ of\ water=1000 kg/m^3 \times {0.023\ m^3}  

Mass of water  = 23 kg

Initial temperature = 16°C  

Specific heat of water = 0.9998 kcal/kg°C  

515=23\times 0.9998\times (T_f-16)

Solving for final temperature as:

<u>Final temperature = 38.3958 °C  </u>

8 0
3 years ago
Bilang mga dalaga at binata, paano nyo lilinangin ang mga aspeto ng tao na inyong taglay?​
Dafna1 [17]

Answer:

Pinagsisikapan kong gawin ang pinakamahusay na tao na maaari akong maging

4 0
3 years ago
Read 2 more answers
How many grams of H2O will be formed when 32.0 g H2 is mixed with 84.0 g of O2 and allowed to react to form water
adell [148]

Answer:

94.57 g H2O

Explanation:

32.0 g H2

Molar Mass H2: 2.01 g/mol

84.0 g O2

Molar Mass O2: 32.00 g/mol

Molar Mass H2O: 18.02 g/mol

First balance the eqution:

2H2 + O2 = 2H2O

Find the amount of moles that both 32.0 g of H2 and 84.0 g of O2 can produce using the molar masses:

32.0 g H2 x ((1 mole H2)/ (2.015 g H2)) = 15.88 moles H2

84.0 g O2 x ((1 mole O2)/(32.00 g O2)) = 2.63 moles O2

Now you can find the amount of grams of H2O each reactant will produce:

**keep in mind of mole ratios from balanced equation**

15.88 moles H2 x ((2 moles H2O)/(2 moles H2)) x ((18.015 g H2O)/(1 mole H2O) =286.07 g H2O

2.63 moles O2 x ((2 moles H2O)/(1 mole O2)) x ((18.015 g H2O)/(1 mole H2O) = 94.76 g H2O

94.76 is the final answer because this is the limiting reactant, meaning it produces less product than the H2 so it limits the reaction from producing anymore product from the amount calculated.

5 0
4 years ago
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