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marissa [1.9K]
3 years ago
8

Sophie is looking at a small particle through a microscope. It has unique proteins in its cell wall, but no nucleus. It is shape

d like a sphere. What is Sophie observing? A. a virus B. a bacterial cell C. an archaeal cell D. a host cell
Chemistry
1 answer:
Rudiy273 years ago
7 0

Answer:

C. an archaea cell

Explanation:

Both bacteria and archaea have a cell wall, but the bacteria cell wall has peptidoglycan. The archaeal doesn't have peptidoglycan, but some unique proteins. They both also don't have nuclei. A virus doesn't have a cell wall, and a host cell, if eukaryote, would have a nucleus.

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Which conditions are necessary for natural selection? Check all that apply.
zepelin [54]

Answer:

Populations have genetic variation.

The environment changes.

Organisms must have specific traits in order to survive and reproduce.

Explanation:

Natural selection provides an advantage during an adverse condition for organisms that have a rich genetic variation in their population.

Also, environmental changes induced natural selection whereby organisms must adapt to changes around them.

For organisms to survive, they must have specific traits that gives them a competitive reproductive advantage.

3 0
3 years ago
Read 2 more answers
Using the equations 2 Sr(s) + O₂ (g) → 2 SrO (s) ∆H° = -1184 kJ/mol SrO (s) + CO₂ (g) → SrCO₃ (s) ∆H° = -234 kJ/mol CO₂ (g) → C(
kkurt [141]

<u>Answer:</u> The \Delta H^o_{rxn} for the reaction is 72 kJ.

<u>Explanation:</u>

Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.

According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.

The given chemical reaction follows:

2SrCO_3(s)\rightarrow 2Sr(s)+2C(s)+3O_2(g)      \Delta H^o_{rxn}=?

The intermediate balanced chemical reaction are:

(1) 2Sr(s)+O_2(g)\rightarrow 2SrO(s)    \Delta H_1=-1184kJ

(2) SrO(s)+CO_2(g)\rightarrow SrCO_3(s)     \Delta H_2=-234kJ      ( × 2)

(3) CO_2(g)\rightarrow C(s)+O_2(g)     \Delta H_3=394kJ    ( × 2)

The expression for enthalpy of the reaction follows:

\Delta H^o_{rxn}=[1\times (\Delta H_1)]+[2\times (-\Delta H_2)]+[2\times (\Delta H_3)]

Putting values in above equation, we get:

\Delta H^o_{rxn}=[(1\times (-1184))+(2\times -(-234))+(2\times (394))]=72kJ

Hence, the \Delta H^o_{rxn} for the reaction is 72 kJ.

4 0
3 years ago
What do elements in the first two columns of the periodic table have in common?
coldgirl [10]

Answer: b.) they tend to lose electrons to gain stability

Explanation:

5 0
3 years ago
PLEASE HELP!!!!!!! <br>Atoms are blank if it has blank electrons in its outer most energy level.
laila [671]
Atoms are (stable) if it has (valence) electrons in its outer most energy level.
4 0
3 years ago
How many liters of space will 7.80 moles of methane gas (CH4) occupy at STP
Alchen [17]

Answer:

V CH4(g) = 190.6 L

Explanation:

assuming ideal gas:

  • PV = RTn

∴ STP: T =298 K and P = 1 atm

∴ R = 0.082 atm.L/K.mol

∴ moles (n) = 7.80 mol CH4(g)

∴ Volume CH4(g) = ?

⇒ V = RTn/P

⇒ V CH4(g) = ((0.082 atm.L/K.mol)×(298 K)×(7.80 mol)) / (1 atm)

⇒ V CH4(g) = 190.6 L

4 0
3 years ago
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