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disa [49]
3 years ago
13

What are the only elements that exist in nature as uncombined

Chemistry
1 answer:
mario62 [17]3 years ago
5 0

Answer:

The noble gases (Argon, Neon, Xenon, Helium, Krypton, Radon)

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3 years ago
Read 2 more answers
How many particles are in 5.0 ml of Fe
nordsb [41]

f it is solid iron, use the density to get the mass. D x V = mass  

Use the mass to find the moles of Fe. Mass/atomic mass = moles  

Moles x Avogadro's number will give you the particles, assuming that you mean atoms.

7 0
3 years ago
I'm not 100% sure of the answer. Explanations are highly appreciated.
PolarNik [594]

Answer:

The correct answer is

B.

\Delta H=2(1072)+498 -4(799)

Explanation:

Enthalpy of reaction :

It is the amount of energy released/absorbed when one mole of the substance is formed from the reactant at a constant pressure.

The enthalpy of a reaction can be calculated using :

\Delta H=\Delta H_{reactants}-\Delta H_{products}

2CO+O_{2}\rightarrow 2CO_{2}

\Delta H_{reactants}=2(C\equiv O)+O=O

\Delta H_{reactants}=2(1072)+498

H_{products}=2(2\times C=O)

H_{products}=4\times 799

\Delta H=\Delta H_{reactants}-\Delta H_{products}

\Delta H=2(1072)+498 -4(799)

units = \frac{kJ}{mole}

Please note that :

The carbon monoxide , CO should be taken as C triple bond O. Not C=O .

So , the bond energy =1072 is used

\Delta H=2(1072)+498 -4(799)

8 0
3 years ago
Define velocity and state what it is meant by uniform acceleration
Arlecino [84]

Velocity- It is basically the speed of an object but with a particular direction.

Uniform Acceleration- It is a type of motion in which the velocity of a object changes by an equal amount in every equal period of time.

7 0
3 years ago
4Al(s) + 30₂(g) → 2Al2O3 (s)
Margaret [11]
1) 1 molecules
2) 2 oxygen atoms
3)2 moles of Al2O3 are formed
4)4:3
6 0
2 years ago
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