1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Blababa [14]
3 years ago
6

Which of the following is true about extinction? A. Only one extinction has occurred during the Earth's history. B. Plant specie

s can become extinct, but animal species cannot. C. Extinctions have occurred many times throughout the Earth's history. D. Animal species can become extinct, but plant species cannot.
Chemistry
2 answers:
ycow [4]3 years ago
8 0

Answer:

C. Extinctions have occurred many times throughout the Earth's history.

Explanation:

lozanna [386]3 years ago
6 0






C.exstinctions have occurred many times
You might be interested in
Which change in the h+ ion concentration of an aqueous solution represents a decrease of one unit on the ph scale?
melisa1 [442]
The answer would be a tenfold increase<span>
The pH scale is calculated based on the concentration of H+ ion in the solution. The formula is using log10, so to decrease 1 unit from the scale it will be 10^1= 10 fold of increase. For 2 </span>unit, you will need 10^2= 100 fold of increase.
6 0
3 years ago
Hydrogen fluoride is used in the manufacture of Freons (which destroy ozone in the stratosphere) and in the production of alumin
Lerok [7]

<u>Answer:</u> The percentage yield of HF is 73.36 %

<u>Explanation:</u>

To calculate the number of moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}     ....(1)  

For calcium fluoride:

Given mass of calcium fluoride = 6.25 kg  = 6250 g   (Conversion factor: 1 kg = 1000 g)

Molar mass of calcium fluoride = 78.07 g/mol

Putting values in above equation, we get:  

\text{Moles of calcium fluoride}=\frac{6250g}{78.07g/mol}=80.05mol

For the given chemical reaction:

CaF_2+H_2SO_4\rightarrow CaSO_4+2HF

By Stoichiometry of the reaction:

1 mole of calcium fluoride produces 2 moles of hydrofluoric acid

So, 80.05 moles of calcium fluoride will produce = \frac{2}{1}\times 80.05=160.1mol of hydrofluoric acid

Now, calculating the theoretical yield of hydrofluoric acid using equation 1, we get:

Moles of of hydrofluoric acid = 160.1 moles

Molar mass of hydrofluoric acid = 20.01 g/mol

Putting values in equation 1, we get:

160.1mol=\frac{\text{Theoretical yield of hydrofluoric acid}}{20.01g/mol}=3203.6g=3.20kg

To calculate the percentage yield of hydrofluoric acid, we use the equation:

\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100

Experimental yield of hydrofluoric acid = 2.35 kg

Theoretical yield of hydrofluoric acid = 3.20 kg

Putting values in above equation, we get:

\%\text{ yield of hydrofluoric acid}=\frac{2.35g}{3.20g}\times 100\\\\\% \text{yield of hydrofluoric acid}=73.36\%

Hence, the percentage yield of HF is 73.36 %

4 0
3 years ago
Use a chemical equation to show how aqueous hno3 fits the definition of an acid
Lunna [17]
An acid has several definitions one would be that it is a proton donor and an electron donor. Also, it said to produce an H+ ion when in solution. For nitric acid in solution, it dissociates into ions which are NO- ions and H+ ions. So, it must be an acid. It has a dissociation reaction:

HNO3 = H+ + NO3-
7 0
3 years ago
For a gaseous reaction, standard conditions are 298 K and a partial pressure of 1 atm for all species. For the reaction N 2 ( g
GuDViN [60]

Answer:

ΔG = -52.9 kJ/mol

Explanation:

Step 1: Data given

Temperature = 298 K

All species have a partial pressure of 1 atm

Δ G ° = − 69.0 kJ/mol

Step 2: The balanced equation

N2(g) + 3H2(g) ⇆ 2NH3 (g)

Step 3: Calculate Q

we will use the expression: ΔG = ΔG° + RT*ln(Q)

⇒with Q = the reaction coordinate: Q = (PNH3)²/ ((PN2)*(Ph2)³) = 666.67

Step 4: Calculate ΔG

So, ΔG = -69.0 kJ/mol + (0.008314 kJ/mol*K)*(298 K)*ln(666.67) = -52.9 kJ/mol

(R = the gas constant = 8.314 J/mol* K OR 0.008314 kJ/mol*K)

4 0
3 years ago
How does bioremediation improve the quality of life for humans?
mart [117]

Completely natural process with almost no harmful side effects

6 0
3 years ago
Other questions:
  • (I seriously don't understand what this questin means, please don't delete need all the help i can get)
    8·2 answers
  • Potassium-40 has a half-life of 1.277 x 109 years. After 1.022 x 1010 years, how much potassium-40 will remain from a 500.3-g sa
    15·2 answers
  • What properties would you expect to be different for the two enantiomers of 2-pentanol?
    14·1 answer
  • At a festival, spherical balloons with a radius of 280. Cm are to be inflated with hot air and released. The air at the festival
    11·2 answers
  • The boiling points of halogens increase in the following order F2 a. ion-dipole<br> b. hydrogen-bonding<br> c. ion-ion<br> d. di
    13·1 answer
  • Which is a type of protein?
    12·2 answers
  • Match the number with the correct type of reaction it is.
    6·2 answers
  • Give a reason why hydroxide ions to an acid solution increase in ph
    13·1 answer
  • An atom or ion has 41 neutrons, 36 protons, and 36 electrons. Identify the clement symbol, and determine the mass
    7·1 answer
  • G.P.E. on Earth is determined by an object's _______and _______
    12·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!