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2 years ago

7. Which of the following changes could be associated with either a chemical change OR a

Chemistry

1 answer:

Elan Coil [88]2 years ago

5 0

Answer:

a: chemical change because the change cannot be reversed.

b: physical change because the action can be reversed.

c: chemical change.

d:chemical change.

any change that cannot be reversed is a chemical change and any change that can be reversed is a physical change.

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Read that From picture and tell me the answer please

Dafna11 [192]

Answer:

1g Hydrogen

Explanation:

<h3>Getting to the equation:</h3>

Calcium in water reacts vigorously to give a cloudy white Precipitate (compound) called Calcium hydroxide alongwith the evolution of Hydrogen gas.

$\boxed{ \mathsf{Ca + H_2O \rightarrow Ca(OH)_2 + H_2}}$

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<h3>Balancing the equation: </h3>

This reaction is not in it's balanced form! The number of atoms of Hydrogen on the left is 2 while that on the right is 4,I.e.,they're not equal.

Adding a 2 in front of H2O solves the problem by making the number of atoms of each element on both the sides equal.

$\mathsf{Ca +2 H_2O \rightarrow Ca(OH)_2 + H_2}$

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

<h3>Observations:</h3>

Looking into the equation more carefully, we see:

1 atom of Calcium reacts with 2 molecules of water to give 1 molecule of Calcium Hydroxide alongwith 1 molecule of Hydrogen gas.

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

<h3>Gram atomic and molecular masses </h3>

Mass of one atom of Calcium = it's gram atomic mass

= 40 g

Mass of one "molecule" of Hydrogen

= it's Gram molecular mass

= gram mass of one atom × number of atoms in one molecule

= 1 × 2

= 2 g

So,

according to our observation:

One atoms of Calcium gives one molecule of Hydrogen (during the particular reaction)

=> 40g of Calcium gives = 2g of Hydrogen

•°• 1 g of Calcium gives = $\frac{2}{40}$

= $\frac{1}{20}$ g Hydrogen

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<h3>Answer:</h3>

We're provided with 20g of Calcium,

=> 20g of Calcium gives = 20 × $\frac{1}{20}$ g H2

= 1 g H2

_______________

Hope this helps!

6 0

2 years ago

Which form of energy does a cheeseburger have

pishuonlain [190]

Answer:

chemical potential energy - It mainly has chemical potential energy, this is really a type of electrical potential energy stored in the chemical bonds of the molecules

Explanation:

You can give the other person brainliest, I don't need it! :)

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3 years ago

In a double-blind test, the non-control group receives a

Aleksandr [31]

Answer:

Hi There! I'm new so I hope I get This Right! ^^

Explanation:

double blind test. the control group receives a placebo. Why is a placebo used in a double-blind test? so that the effects on people in two different groups can be compared.

happy To Help! ^^

6 0

3 years ago

Elements symbol

Marat540 [252]

1) H
2) He
3) Li
4) Be
5) B
6) C
7) N
8) O
9) F
10) Ne
11) Na
12) Mg
13) Al
14) Si
15) P
16) S
17) Cl
18) Ar
19) K

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3 years ago

The thermostat in a refrigerator filled with cans of soft drinks malfunctions and the temperature of the refrigerator drops belo

butalik [34]

Answer:

Explanation:

Water expands on freezing and there is more water in the diet drinks than in the other drinks.

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3 years ago

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