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lorasvet [3.4K]
4 years ago
13

Which of the following involve chemical changes?

Chemistry
1 answer:
natita [175]4 years ago
7 0

1 and 2 are both chemical changes because they can not be reversed while 3 is only changing states and can be reversed by freezing the melted chocolate.

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24. The air in a small 250 cm birthday balloon is at a pressure of 760 torr. A boy sits on it at
kvv77 [185]

Answer:

1.14atm

Explanation:

Given parameters:

V1 = 250cm³ ;

              1000cm³ = 1dm³;  so this is 0.25dm³

P1  = 760torr

            760torr  = 1atm

       

V2  = 220cm³ ; 0.22dm³

Unknown:

New pressure = ?

Solution:

To solve this problem, we apply Boyle's law and we use the expression below:

       P1 V1 = P2V2

The unknown is P2;

            1 x 0.25  = P2 x 0.22

                 P2  = 1.14atm

7 0
3 years ago
In your opinion, why do you think the atomic models are not final?
julia-pushkina [17]

Answer:

because they change

Explanation:

It was based on theories and discoveries

7 0
3 years ago
if an iron nail is placed in a glass of water the nail will sink. Is the density of iron smaller than or larger than the density
Gala2k [10]
It has  more density when it sinks because the water pushes away thats why people float they are less dense 
5 0
3 years ago
How much heat is required to raise the temperature of 81.0 g of water from its melting point to its boiling point?
Dovator [93]

Answer:

Specific heat of water = 33.89 KJ

Explanation:

Given:

mass of water = 81 gram

Initial temperature = 0°C

Final temperature = 100°C

Specific heat of water = 4.184

Find:

Required heat Q

Computation:

Q = Mass x Specific heat of water x (Final temperature - Initial temperature)

Q = (81)(4.184)(100-0)

Q = 33,890.4

Specific heat of water = 33.89 KJ

6 0
3 years ago
How many protons, and neutrons are in nuclide tin-115?
HACTEHA [7]
50 protons
65 neutrons
8 0
3 years ago
Read 2 more answers
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