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nata0808 [166]
2 years ago
13

True or False:

Chemistry
1 answer:
lesya [120]2 years ago
6 0

Answer:

False

Explanation:

  • Mendeleev was the first scientist to arrange the element in such a periodic order but there was a mistake that he arranged in increasing order of mass.
  • Today we use the periodic table given by Henry Mosley where atomic no is first priority
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Fill in the blanks: when an atom absorbs energy, the electrons move from their _________________ state to an _________________ s
Lorico [155]
<span>Fill in the blanks: when an atom absorbs energy, the electrons move from their (ground) state to an (excited) state. when an atom emits energy, the electrons move from a(n) (excited) state to their (ground) state and give off (energy)</span>
3 0
3 years ago
Which of these is an ionic compound?<br> NO2<br><br> LiCl<br><br> SO3<br><br> CO
Pavlova-9 [17]
It is "LICI" I believe. I could be wrong please let me know if I am wrong.
4 0
3 years ago
Read 2 more answers
Write three sentences about The Amazing Life of Sand<br> HELP ASAP PLS
pishuonlain [190]

Answer:“If we’ve covered all of the potential sources, and we know the unique signature of the sand from these different sources, and we find it on a beach somewhere, then we basically know where it came from,” explained Barnard.

Explanation:

7 0
3 years ago
2Al(s) + Fe2O3(s) → Al2O3(s) + 2Fe(s) T
brilliants [131]

Answer:

ΔHrxn = [(1) -1675.5 ( kJ/mole) + (2) 0 ( kJ/mole)] - [(1) -824.3 ( kJ/mole) + (2) 0 ( kJ/mole)]

Explanation:

ΔHrxn = 2ΔHf (Al₂O₃)  - ΔHf (Fe₂O₃)

Remember that for pure elements in their standard state of temperature and pressure by definition their standard heats of formation are zero.

ΔHrxn = 2(-1675.7) - (-824.3) kJ/mol

ΔHrxn = 2527 kJ/mol

6 0
3 years ago
Given the equation C3H8(g) + O2(g) = CO2(g) + H2O(g) and that the enthalpies of formation for H2O(g) = -241.8 kJ/mol, CO2(g) = -
kari74 [83]

Answer: 72.4 kJ/mol

Explanation:

The balanced chemical reaction is,

C_3H_8(g)+5O_2(g)\rightarrow 3CO_2(g)+4H_2O(l)  \Delta H=-2220.1kJ/mol

The expression for enthalpy change is,

\Delta H=\sum [n\times \Delta H_f(product)]-\sum [n\times \Delta H_f(reactant)]

\Delta H=[(n_{CO_2}\times \Delta H_{CO_2})+(n_{H_2O}\times \Delta H_{H_2O})]-[(n_{O_2}\times \Delta H_{O_2})+(n_{C_3H_8}\times \Delta H_{C_3H_8})]

where,

n = number of moles

\Delta H_{O_2}=0 (as heat of formation of substances in their standard state is zero

Now put all the given values in this expression, we get

-2220.1=[(3\times -393.5)+(4\times -241.8)]-[(5\times 0)+(1\times \Delta H_{C_3H_8})]

\Delta H_{C_3H_8}=72.4kJ/mol

Therefore, the heat of formation of propane is 72.4 kJ/mol

7 0
3 years ago
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