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4 years ago

How are physical andchemical changes different?

1 answer:

5 0

Physical changes happen when you do/mix something that can be reversed. Best example is ripping a paper, you can just tape it back together so it is just an observable thing that changes, which is a physical change. Chemical changes happen when you mix things and they make a new substance and can’t be reversed. The best example of this is the Statue of Liberty, which changed in color due to the chemical change between the oxygen and copper, which created a new substance (rust) which made it green instead of copper.
Sorry for the long answer but hope this helps!

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Thirst is triggered when total body water decreases by as little as

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The Answer to the question is:

:1%

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3 years ago

Which statement BEST describes what happens when a cold front approaches a warm front?

stepladder [879]

Answer:

Explanation:

In a cold front set-up, the boundary between the cold and warm air masses is relatively steep, typically causing the warm air in front of it to rise rapidly.

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3 years ago

Read 2 more answers

Determine the number of unpaired electrons in Ca?

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When an electron occupies an orbital of an atom singly, rather than an electron pair such electron is said to be an unpaired electron. Each atomic orbital of an atom specified by quantum numbers can contain a maximum of two electrons having opposite spins, electron pair.

The numbers of unpaired electrons are determined by the electronic configuration of an atom. The electronic configuration of calcium, $Ca$ is:

$1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}$ or $[Ar]4s^{2}$

Since, from the electronic configuration it is clear that the number of electrons in valence orbital that is $4s$ is 2 that means the electrons are paired up in the valence orbital so, there are no unpaired electrons present in $Ca$ .

Hence, the number of unpaired electrons in $Ca$ is 0.

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3 years ago

Metal M has only one oxidation state and forms a compound with the formula MHCO3. Which formula is correct? A.MNO3 b.MNH4 c.M(NO

never [62]

Answer:

The compound with the correct formula is;

A. MNO₃

Explanation:

The number of oxidation states in the metal, M = One oxidation state

The formula of the compound formed by the metal, M = MHCO₃

We note that the ion HCO₃⁻, known as hydrogen carbonate has an oxidation number of -1

Similarly nitrate, NO₃⁻ has an oxidation number of -1, therefore, the metal M can form similar compound formed with HCO₃⁻ with nitrate, and we have;

The possible compounds formed by the metal 'M' includes MHCO₃ and MNO₃.

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3 years ago

Hydrazine (n2h4) is used as rocket fuels. it reacts with oxygen to form nitrogen and water. write the balanced equation for this

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The answer is: volume of nitrogen is 70L.

Chemical reaction: N₂H₄ + O₂ → N₂ + 2H₂O.

m(N₂H₄) = 100 g; mass of hydrazine.

M(N₂H₄) = 32 g/mol; molar mass of hydrazine.

n(N₂H₄) = m(N₂H₄) ÷ M(N₂H₄).

n(N₂H₄) = 100 g ÷ 32 g/mol.

n(N₂H₄) = 3.125 mol; amount of hydrazine.

m(O₂) = 100 g; mass of oxygen.

M(O₂) = 32 g/mol; molar mass of oxygen.

n(O₂) = 100 g ÷ 32 g/mol.

n(O₂) = 3.125 mol; amount of oxygen.

From chemical reaction: n(O₂) : n(N₂) = 1 : 1; n(O₂) = n(N₂).

n(N₂) = 3.125 mol; amount og nitrogen gas.

V(N₂) = n(N₂) · Vm.

Vm = 22.4 L/mol; molar volume.

V(N₂) = 3.125 mol · 22.4 L/mol.

V(N₂) = 70 L.

There is not excess reagent, because hydrazine and oxygen are all used in chemical reaction.

5 0

3 years ago

How are physical andchemical changes different?​

How are physical andchemical changes different?