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3 years ago

PLEASE HELP ASAP 100 POINTS!!!!!

Chemistry

2 answers:

Vilka [71]3 years ago

8 0

Answer:

Melting

Explanation:

• A chemical change is a change that can be reversed.

Other chemical changes include;

Melting (solid to liquid)
Evaporation (liquid to gas)
Condensation(gas to liquid)
Sublimation (solid to gas and gas to solid)
$.$

Reptile [31]3 years ago

7 0

The answer is burning

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A neutral isotope has 49 neutrons and 36 electrons. Identify the element symbol of this isotope and determine the mass number an

Marta_Voda [28]

Explanation:

In an atom , the relation between the subatomic particles of the atom are given as follows -

For a neutral atom ,

Atomic number = number of protons = number of electrons ,

Mass number = number of protons + number of neutrons,

Hence , from the given information of the question,

number of neutrons = 49 ,

number of electrons = 36 ,

Hence , by using the above relation,

Atomic number = 36

number of protons = 36

Since ,

Mass number = number of protons + number of neutrons

Mass number = 36 + 49 = 85 .

By taking the help of periodic table , as atomic number = 36 ,

The elements is Krypton ( Kr )

Kr ⁸⁵₃₆

4 0

4 years ago

Describe two physical and two chemical changes involved in cooking. (4 points)

Ivenika [448]

Physical changes are when things get changed without altering chemical consistencies, which is melting solid butter into liquid one, or boiling water. Chemical changes are things such as caramelizing sugar when making sweets, or when carbon dioxide is created and released when baking bread.

7 0

4 years ago

If 1.20 moles of copper react with mercuric nitrate how many moles of mercury form

Andrej [43]

Reaction of Copper with Mercuric Nitrate is as follow,

Cu + Hg(NO₃)₂ → Cu(NO₃)₂ + Hg

According to equation,

1 Mole of Cu reacts to form = 1 Mole of Hg

So,

1.20 Moles of Cu will react to produce = X Moles of Hg

Solving for X,

X = (1.20 mol × 1 mol) ÷ 1 mol

X = 1.20 mol of Hg
Result:
1.20 mole of Cu when reacted with mercuric nitrate produces 1.20 moles of Hg.

3 0

4 years ago

A gas with a volume of 15L at 640K is cooled at a constant pressure until the volume reaches 5L. What is the new temperature?

Brut [27]

Answer:

The new temperature is 213.33 K

Explanation:

Charles's law indicates that the volume of gas at constant pressure is directly proportional to its temperature. This law indicates that if the temperature increases the volume increases and if the temperature decreases the volume decreases.

So, Charles's law is a law that says that when the amount of gas and pressure are kept constant, the ratio between volume and temperature will always have the same value:

$\frac{V}{T}=k$

When you want to study two different states, an initial and a final one of a gas, the expression can be applied:

$\frac{V1}{T1} =\frac{V2}{T2}$

In this case, you know:

V1= 15 L
T1= 640 K
V2= 5 L
T2=?

Replacing:

$\frac{15 L}{640 K} =\frac{5 L}{T2}$

Solving:

$T2=\frac{5 L}{\frac{15 L}{640 K} }=\frac{5 L*640 K}{15 L}$

T2= 213.33 K

<u><em>The new temperature is 213.33 K</em></u>

8 0

3 years ago

An object was measured by a worker as

Gre4nikov [31]

Answer:

$\boxed{2.8 \, \%}$

Explanation:

$\text{Percent error} = \dfrac{\lvert \text{Measured - Actual}\lvert}{ \text{Actual}} \times100 \, \%$

Data:

Predicted = 17.4 cm

Actual = 17.9 cm

Calculation:

$\text{Percent error} = \dfrac{\lvert 17.4 - 17.9\lvert}{17.9} \times 100 \, \% \\\\= \dfrac{\lvert-0.5\lvert}{17.9} \times 100 \, \% = \dfrac{0.5}{17.9} \times 100 \, \% \\\\= 0.028 \times 100 \, \% = \textbf{2.8 \%}\\\\\text{The percent error in the measurement is } \boxed{\textbf{2.8 \%}}$

6 0

3 years ago