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djyliett [7]
3 years ago
10

3. Mrs Green bakes muffins.

Mathematics
1 answer:
Sphinxa [80]3 years ago
8 0

Answer:

85%

Step-by-step explanation:

Monday:

200 x 0.70 = 140

200 - 140 = 60

Tuesday:

400 x ? = 60

400 x 0.85 = 340

400 - 340 = 60

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The arnold family arrived at the beach at 10:30 a.m. The spent 3 3/4 hours there. what time did they leave the beach?
Dennis_Churaev [7]
2:15 was the time they left the beach
4 0
3 years ago
When electricity (the flow of electrons) is passed through a solution, it causes an oxidation-reduction (redox) reaction to occu
oee [108]

Answer:

a. 135 g

b. 60.6 min

Step-by-step explanation:

a. What mass of Cu(s) is electroplated by running 28.5 A of current through a Cu2+ (aq) solution for 4.00 h? Express your answer to three significant figures and include the appropriate units.

The chemical equation for the reaction is given below

Cu²⁺(aq) + 2e⁻ → Cu(s)

We find the number of moles of Cu that are deposited from

nF = It where n = number of moles of electrons, F = Faraday's constant = 96485 C/mol, I = current = 28.5 A and t = time = 4.00 h = 4.00 × 60 min/h × 60 s/min = ‭14,400‬ s

So, n = It/F = 28.5 A × ‭14,400‬ s/96485 C/mol = ‭410,400‬ C/96485 C/mol = 4.254 mol

Since 2 moles of electrons deposits 1 mol of Cu, then 4.254 mol of electrons deposits 4.254 mol × 1 mol of Cu/2 mol = 2.127 mol of Cu

Now, number of moles of Cu = n' = m/M where m = mass of copper and M = molar mass of Cu = 63.546 g/mol

So, m = n'M

= 2.127 mol × 63.546 g/mol

= 135.15 g

≅ 135 g to 3 significant figures

b. How many minutes will it take to electroplate 37.1 g of gold by running 5.00 A of current through a solution of Au+(aq)?

The chemical equation for the reaction is given below

Au⁺(aq) + e⁻ → Au(s)

We need to find the number of moles of Au in 37.1 g

So, number of moles of Au = n = m/M where m = mass of gold = 37.1 g and M = molar mass of Au = 196.97 g/mol

So, n = m/M = 37.1 g/196.97 g/mol = 0.188 mol

Since 1 mol of Au is deposited  by 1 moles of electrons, then 0.188 mol of Au deposits 0.188 mol of Au × 1 mol of electrons/1 mol of Au = 0.188 mol of electrons

We find the time it takes to deposit 0.188 mol of electrons that are deposited from

nF = It where n = number of moles of electrons, F = Faraday's constant = 96485 C/mol, I = current = 5.00 A and t = time

So, t = nF/It

= 0.188 mol × 96485 C/mol ÷ 5.00 A

= ‭18173.30‬ C/5.00 A

= 3634.66 s

= 3634.66 s × 1min/60 s

= 60.58 min

≅ 60.6 min to 3 significant figures

6 0
3 years ago
Solve the equation m=2n-p
allsm [11]

Here is your answer:


Move all terms with m to the left, all other terms to the right:


m + 2n + -2n = -2n + p

Combine like terms:

2n + -2n = 0

m + 0 = -2n + p

Which would equal "m = -2n + p" after you simplify.


Hope this helps!


~Nonportrit

3 0
3 years ago
What is the value of (12-5)^2+22-3
charle [14.2K]
Using PEMDAS, 12-5 is 7. 7^2 is 49. 49+22=71. 71-3=68.
8 0
3 years ago
Read 2 more answers
Someone plz help me!!!! :(
dlinn [17]

Answer:

Check the explanation

Step-by-step explanation:

Part A: the sum of Side 1 and Side 2= 5x^2+7x-4

Part B all you have to do is the same thing, but subtract the sum of side 1 and 2 from the total. 5x^3-0x^3=? 4x^2-5x^2=? -x-7x=? -3-4=?

Part C:The closure property states that one polynomial plus another polynomial is also a polynomial. It is the same for addition, subtraction, multiplication, and division

6 0
3 years ago
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