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3 years ago

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If the neutral atom of an element has only 4 valence electrons it must be in which group? 1. IVB 2. VA 3. VIIA 4. VIA 5. IVA 6.

IIIA

1 answer:

lisabon 2012 [21]3 years ago

5 0

Answer:option

Option 5..IVA

Explanation:

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Hippopotamus as an animal

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Answer:

The common hippopotamus, or hippo, is a large, mostly herbivorous, semiaquatic mammal and ungulate native to sub-Saharan Africa. It is one of only two extant species in the family Hippopotamidae, the other being the pygmy hippopotamus. The name comes from the ancient Greek for "river horse".

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Hydrogen, a potential future fuel, can be produced from carbon (from coal) and steam by the following reaction: C(s)+2H2O(g)→2H2

madam [21]

The question is incomplete , complete question is:

Hydrogen, a potential future fuel, can be produced from carbon (from coal) and steam by the following reaction:

$C(s)+ 2 H_2O(g)\rightarrow 2H_2(g)+CO_2(g).\Delta H=?$

Note that the average bond energy for the breaking of a bond in CO2 is 799 kJ/mol. Use average bond energies to calculate ΔH of reaction for this reaction.

Answer:

The ΔH of the reaction is -626 kJ/mol.

Explanation:

$C(s)+ 2 H_2O(g)\rightarrow 2H_2(g)+CO_2(g).\Delta H=?$

We are given with:

$\Delta H_{H-O}=459 kJ/mol$

$\Delta H_{H-H}=432 kJ/mol$

$\Delta H_{C=O}=799 kJ/mol$

ΔH = (Energies required to break bonds on reactant side) - (Energies released on formation of bonds on product side)

$\Delta H=(4\times \Delta H_{O-H})-(2\times \Delta H_{H-H}+2\times\Delta H_{C=O})$

$=(4\times 459 kJ/mol)-(2\times 432 kJ/mol+2\times 799 kJ/mol$

$\Delta H=-626 kJ/mol$

The ΔH of the reaction is -626 kJ/mol.

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Answer:

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If 450.0 mL of a 0.500 M solution is mixed with 200.0 mL of water, what is the molarity of the new

Oksana_A [137]

Answer:

Answer: A) .346 M

Explanation:

Given:

- 450 mL

- .5 M soln

-200 mL water

1) Convert mL to L

450 mL = .45 L

200 mL = .2 L

2) Find mols in solution

.5 M = x/.45 L

x = .225 mol

3) Find total volume of solution

.45 L + .2 L =.65 L

4) Find new molarity

molarity (M) = mols solute/ L solution

y = .225 mol (from step 2)/ .65 L (from step 3)

y = .346 M

Answer: A) .346 M

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