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4 years ago

Which is true of ultraviolet rays?

1 answer:

7 0

A is true of UV rays.
B is true not of UV rays but rather of visible light.
C is true not of UV rays but rather of microwaves. (unless you actually toast your toast in a toaster like a normal person)
D is true not of UV rays but rather of radio waves.

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I really need help with this science question please please please help me

umka2103 [35]

B, Because the classroom started with cylinder cups they should add 7mL into the cup and then transfer the 7mL on the cups

6 0

3 years ago

An athlete has 13

FrozenT [24]

Answer = 23.2146762081 pounds.
-------------------------------------------------

13% of 81 = 10.53
10.53 converted to pounds (lbs) = 23.21......pounds

6 0

3 years ago

What does “Alkali” mean???

zvonat [6]

It doesn't exactly mean anything, but it does describe the second group of elements, the Alkali Earth Metals.

4 0

3 years ago

How many grams of carbon dioxide are created from the complete

ololo11 [35]

Answer:

167.2 g

Explanation:

Known

VC4H10 = 21.3

T = 0.00 C (convert to Kelvin: 273 K)

P = 1.00 atm

Unknown

m = ?g

1. Write the balanced chemical equation

1 C4H10 + 1O2 -----> 4 CO2 + 5 H2O

2. Find the volume ratio of Carbon Dioxide to Butane

1 C4H10 4 CO2 = 4 volumes CO2 / 1 volume C4H10

3. Multiply by the known volume of n (butane)

21.3 L C4H10 x 4 volumes CO2 / 1 volume C4H10 = 85.2 L C4H10

4. Use ideal gas law

PV = nRT solve for n ----> n = PV/RT

n= (1.00 atm) (85.2 L) / (0.0821 L atm/mol K) (273) = 3.80 mol CO2

5. Find molar mass of CO2

1 C x 12 + 2 O x 16 = 44.00

6. Multiply the ideal gas law solution (3.80) by molar mass CO2 (44.00)

3.80 mol CO2 x 44.00 g CO2

= 167.2 g CO2

7 0

3 years ago

Mg(OH)2 + 2 HBr à MgBr2 + 2 H2O

AnnyKZ [126]

Explanation:

The balanced equation of the reaction is given as;

Mg(OH)2 (s) + 2 HBr (aq) → MgBr2 (aq) + 2 H2O (l)

1. How many grams of MgBr2 will be produced from 18.3 grams of HBr?

From the reaction;

2 mol of HBr produces 1 mol of MgBr2

Converting to masses using;

Mass = Number of moles * Molar mass

Molar mass of HBr = 80.91 g/mol

Molar mass of MgBr2 = 184.113 g/mol

This means;

(2 * 80.91 = 161.82g) of HBr produces (1 * 184.113 = 184.113g) MgBr2

18.3g would produce x

161.82 = 184.113

18.3 = x

x = (184.113 * 18.3 ) / 161.82 = 20.8 g

2. How many moles of H2O will be produced from 18.3 grams of HBr?

Converting the mass to mol;

Number of moles = Mass / Molar mass = 18.3 / 80.91 = 0.226 mol

From the reaction;

2 mol of HBr produces 2 mol of H2O

0.226 mol would produce x

2 =2

0.226 = x

x = 0.226 * 2 / 2 = 0.226 mol

3. How many grams of Mg(OH)2 are needed to completely react with 18.3 grams of HBr?

From the reaction;

2 mol of HBr reacts with 1 mol of Mg(OH)2

18.3g of HBr = 0.226 mol

2 = 1

0.226 = x

x = 0.226 * 1 /2

x = 0.113 mol

5 0

3 years ago