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BabaBlast [244]
3 years ago
14

I need help with this

Mathematics
1 answer:
andrew11 [14]3 years ago
4 0

Answer:

a)  5(12+7)

b) 5(19)=95

Step-by-step explanation:

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!/8 pound of fertilizer covers 25 square feet of ground, how much fertilizer, in pounds, is needed to cover 1 square foot ground
suter [353]

Answer:

  • 1/200 pounds

Step-by-step explanation:

<u>Given ratio</u>

  • 1/8 pound ⇔ 25 square feet

<u>To find </u>

  • x ⇔ 1 square foot

<u>Divide both sides by 25</u>

  • 1/8÷25 pounds ⇔ 25÷25 square feet
  • 1/200 pounds ⇔ 1 square foot
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2 years ago
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Today, Barry wants to write at least 50 pages of his research paper. Barry wrote 18 pages this morning. Barry averages about 8 p
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The answer is

Step-by-step explanation:

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2 years ago
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Enter the coordinates of the point on the unit circle at the given angle. 135° (-VII, VI Enter​
vekshin1
Related angle is 45 degrees, set up a triangle and use exact trig values to solve for x and y, then rationalise the denominators

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
2 years ago
Hassan's backyard swimming pool is 30 feet long, 20 feet wide, and 5 feet deep. there are 7.5 gallons of water in 1 cubic foot.
cricket20 [7]
Find how many cubic feet
cubic feet=length times width times height for rectangle prism

volume=30 times 20 times 5=3000 cubic feet

7.5 per 1 cubic feet
times 3000
22500 gallons
3 0
3 years ago
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